Elementary School Math Problems Profit and Loss Primary School Math Formulas Encyclopedia Profit and

6+4+4 2) (5-4) 18 (Kindergarten) 18+2 20 (Kindergarten)

18 5-6 84 (block).

Solution: Assuming that the number of people in the small class is the same as the number of people in the large class, then each person in the small class is given 4 pieces of candy, then there will be 4 more pieces of the original and 8 pieces more after the later assumption.

Answer: 84 people.

Solution: (6+4+4*2) (5-4) 18 people (large class size) 18 + 2 20 people (small class size).

18*5-6 84 blocks or 20*4+4 84 blocks Description: The key is to understand the meaning of 4+4*2, which means that if the number of people in the small class is the same as that of the large class, if each person in the small class is given 4 pieces, there will be a total of extra (4+4*2) blocks.

Answer: 84 people.

Solution: (6+4+4*2) (5-4) 18 people (large class size) 18 + 2 20 people (small class size).

18*5-6 84 pieces or 20*4+4 84 pieces.

Note: The key is to understand the meaning of 4+4*2, which means that if the number of people in the small class is as large as that in the large class, if each person in the small class is given 4 yuan, there will be a total of extra (4+4*2) blocks.

There are x people in the large class, and they have to:

5x-6=4(x+2)+4

Solution: x=18

This pack of sugar has a total of (5x-6) = 84 pieces.

84, there are x people in the large class, 5x-6 = 4 (x + 2) + 4, x = 18, and 84 people are brought in.

The profit and loss problem: It was developed on the basis of equal division. His characteristic is to distribute a certain number of items evenly to a certain number of people, in two distributions, one is surplus, one is insufficient (or both are insufficient), or both are insufficient), the number of surplus and insufficient is known, and the problem of finding the appropriate amount of goods and the number of people participating in the distribution is called the profit and loss problem.

The key to solving the problem: the key point of solving the profit and loss problem is to first find the difference between the number of items that the distributor did not get in the two distributions, and then find the difference between the items shared in the two distributions (also known as the total difference), and use the previous difference to remove the latter difference to obtain the number of distributors, and then find the number of items.

Problem solving rule: total difference per person difference = number of people.

The total difference can be divided into the following four cases:

The first time is redundant, the second time is insufficient, the total difference = excess + insufficient.

The first time is good, the second time is redundant or insufficient, and the total difference = excess or insufficient.

The first time is redundant, the second time is also redundant, total difference = mostly redundant - small redundant.

The first judgment is insufficient, the second is also insufficient, Total Difference = Big Deficiency - Small Deficiency.

For example, if there are 10 people in the group, there will be 25 more colored pens, and if there are 12 people in the group, there will be more than 5 colored pencils. How many sticks do you want to get for each person? How many colored pencils are there?

Analysis: Each student was given an equal number of colored pens. There were 12 people in this activity group, 2 more than 10 people, and 20 more coloring pens (25-5), 2 more than 20 people, and 10 more for one person.

The column formula is (25-5), 12-10, 10 (branches), 10 12+5=125 (branches).

The difference in the total number of differences in each serving The number of copies Q1: (10-9) 1=1 There is 1 child with pure width Substitute 1 person with a child: 1*3+10 or 1*4+7+2=13 There are 13 pieces of candy Q2:

Profit: 5*4=20 Loss: 5*2=10 (20+10) (5-4)=30 30 students 30 students 30*4+5*4 or (30-2)*5=140 There are 140 bricks.

1.The old teacher of the kindergarten town pants took out the candy and handed it out to the children. 3 yuan per person, more than 10 yuan; If you reduce 2 pieces.

4 pieces per person, 7 more. Ask how many children there are.

How many pieces of candy are there? Suppose there are x children and the total number is y: 3x+10=y---1) 4x+7=y-2 4x+7=y-2 4x+7+2=y 4x+9=y---2) 3x+10=4x+9 3x+1=4x x=1 and x is 1 3*1+10=y 13=y There are 1 children with a total of 13 pieces of candy 2

Some students move a batch of bricks.

Each person moves 4 pieces.

Five of them had to move twice; If you move 5 pieces per person.

There were two people who had no bricks to move.

How many of these students are there? How many bricks are there? Let x be the number of people and y be the number of bricks:

4x+5(2-1)*4=5x-10 4x+20=5x-10 4x+20+10=5x 4x+30=5x x=30 x is known to be 30

4x+5(2-1)*4 and 5x-10 are both y 4*30+20=y 120+20=y 140=y

Reference: me

Basic concept: a certain amount of objects, grouped according to a certain standard, produces a result: grouped according to another standard, scattered potatoes produce another result, due to the different standards of grouping, resulting in the difference of results, by their relationship to find the number of groups of objects grouped or the total amount of objects.

The basic idea: first compare the two distribution schemes, analyze the changes in the results caused by the difference in standards, find the total number of shares participating in the distribution according to this relationship, and then find the total number of objects according to the topic.

Basic question type: one with a remainder, another with a deficiency;

The basic formula: the difference between the total number of parts (the remainder and the insufficient number) of the number of each part twice.

When there is a remainder both times;

The basic formula: the total number of copies (the greater remainder and the smaller remainder) are the difference between the number of copies per two times.

When both times are insufficient;

The basic formula: the difference between the total number of copies (the greater number of lesser copies and the smaller number of less) twice for each number of copies.

Basic features: The total number of objects and the total number of groups are constant.

Key Question: Determine the total number of objects and the total number of groups.

Example 1: A class of a certain unit of the People's Liberation Army participates in afforestation activities. If each person plants 5 saplings, there are 14 saplings left; If each person plants 7 trees, there is a difference of 4 saplings. How many people are in this class? How many saplings are there.

Analysis: From the conditions, it can be seen that this question belongs to the first case. Column: (14 4) (7 5) 18 2 9 (person).

5 9 14 45 14 59 or: 7 9 4 63 4 59 (tree).

A: There are 9 students in this class, and there are 59 saplings in total.

Example 2: The school distributes some colored pencils to the students in the art group, if each person is given 5 sticks, there will be 45 sticks left, and if each person is given 7 sticks, there will be 3 sticks left. How many students are there in the art group? How many colored pencils are there?

45 3) (7 5) 21 (person).

21 5 45 150 (branches) Answer: Omitted.

(P&L + P&L) The difference between the two distributions = the number of shares.

70+5) 5=15 cars.

15 65 + 5 = 980 people.

The easiest way to do this is to set an equation.

There are a total of x cars and y students.

65x+5=y

70x-70=y

x=15

y=980 so there are 15 cars, 980 students.

65+5 70 70 5 65 70 65 65 65 65 65 65 5 330

A: There are 5 buses and 330 students.

There are y students first, and x car is 65x+5=y

70（x-1）=y

Subtract the two formulas: 5x-65=0

This gives us x=13

Substituting x=13 into the above equation gives y=840.

So there are 13 cars and 840 students.

Each card is 5 jiao, and each card is 1 yuan and 2 jiao, so the money brought by Lele is a common multiple of 5 and 12, and the minimum is 60 jiao. After testing, 60 does not meet the topic, then use the expansion method to calculate.

120 jiao, you can buy 24 pieces of 5 jiao, you can buy 10 pieces of 1 yuan and 2 jiao. 24-8 = 10 + 6 = 16 sheets.

So Lele brought 12 yuan, and each card was 120 16 = corner = 7 corners and 5 points.

Solution: Shele brought T yuan, B X yuan.

t gets t=12, 24 for A, 10 for C, and 16 for B.

x=12/16=

So it's a total of 12 yuan, and B yuan per piece.

The number of A and C cards is compared with B cards, so if you buy the same number of cards as B cards: there are 5 * 8 40 jiao left to buy a type A card, and there is still 6 * 12 72 jiao left to buy a C card. According to the formula of the profit and loss problem, it is obtained:

72+40) (12 7) 16 cards B (16+8) * 5 120 corners.

120 16 7 jiao 5 points.

Brought 12 yuan, B card for each corner.

With all the money that Lele brought, he has to buy 8 more cards than he buys cards B, and 6 more cards to buy cards than he buys cards C.

Explain Lele's money, buying a card is 8 + 6 = 14 more than buying a C card, and the extra 14 A cards are 5 14 = 70 jiao, and each A card is 12-5 = 7 jiao cheaper than the C card.

Therefore, you can buy 70 7 = 10 cards for C card, and Lele brings 12 10 = 120 corners, that is, 12 yuan.

B card can buy 10 + 6 = 16 pieces, then its unit price is 12 16 = 3 4 yuan, that is, 7 jiao 5 points per card.

Solution: Shele brought Y Yuan, B X Yuan.

y y=12, A: 24 sheets, C: 10 sheets, B: 16 sheets.

x=12/16=

Answer: Lele brought 12 yuan, and each card was 12 yuan.

1.One day, the teacher of Congcong Kindergarten distributed apples to the kindergarten children. If each person divides 4, 10 more; If each person divides 5, it is 8 less. Do you know how many children are in this class? How many apples do they share?

2.Use a rope to measure the depth of the well, if the rope is folded 3, the outside of the well is 2 meters more; If the rope is folded 4 times, there is still less than 1 meter of the wellhead. How many meters deep is the well? How many meters is the rope long?

4.The No. 2 Experimental Primary School of the city organized students to participate in the science and technology exhibition. If there are 75 people in each car, 5 people will not be able to ride; If you sit for 5 more points per car, you will have one more car. How many cars are there on this tour? How many students are there?

3.The school conducts a general cleaning and assigns students to clean glass. Two of them rubbed 4 pieces each, and the rest rubbed 5 pieces each, leaving 12 pieces; If each person rubs 6 pieces, it is exactly finished. Can you help the Labor Council calculate how many pieces of glass to wipe? How many people do I need to clean glass?

60 pieces. 4.Liang Liang leaves home on time at 7 o'clock every morning to go to school. If you walk 60 meters per minute, you will be 3 minutes late for class; If you walk 70 meters per minute, you can arrive at school 2 minutes earlier. How many meters is Liangliang's home from school?

x/60－3=x/70＋2

x/60－x/70=5

x=2100

5.Lei Feng's team moved bricks for the school. If each person moves 18 pieces, there are 2 pieces left; If each person moves 20 bricks, there is a student who has no bricks to move. How many bricks are there?

20 2+1=11 people.

11 18 + 2 = 200 blocks.

6.arrange student dormitories, if there are 5 people per room, 14 people do not have beds; If there are 7 people per room, there are 4 more beds. How many dormitories are there? How many students are there?

9 5 14 = 59 people.

7.If a car travels from A to B at a speed of 10 kilometers per hour, it arrives 2 hours in advance. At a speed of 8 kilometers per hour, it is 3 hours late. How many kilometers are A and B apart?

10 2 + 8 3) (10-8) = 22 (hours).

22-2) 10=200 (km).

7.The aunt divides a bunch of candy to the kindergarten children, if each person divides 10 pieces, it will be 8 more pieces; If each person gets 12 pieces, there is just one child who doesn't get the candy. How many more pieces do I need to add to get 11 pieces of candy for each child?

8.In the rope skipping competition between classes, 2 groups each borrowed 4 ropes, and the rest of the groups borrowed 5 ropes, so that the remaining 12 ropes were distributed in the end; If each group borrows 7 sticks, it will be exactly the end of the loan. How many ropes are there?

12-(5-4) 2] (6-5)=10 (set);

6 10 = 60 (root).

9.There are several red and white balls. If you take out 1 red ball and 1 white ball at a time, when you get no red ball, there are 50 white balls left; If you take 1 red ball and 3 white balls at a time, you will have 50 red balls left when there are no white balls.

So how many red and white balls are there in this pile?

x-[x+100]÷3=100

x=100 is not even such an easy question.b Khan.