Mathematics for junior high school Simple column equation solving application problems Thank you for

1) When the number of people is 30 people.

A travel agency: 40*10+40*

800 (yuan).

B Travel Agency: 40*

720 (yuan).

When the number of people is 30, travel agency B is cheaper.

When the number of people is 70.

A travel agency: 40*10+40*

1600 (yuan).

B Travel Agency: 40*

1680 (yuan).

When the number of people is 70 people, A travel agency is cheaper.

2) When the number of people is set to x.

Travel agency A = travel agency B.

x=50A: When the number of people is 50, the ** of the two travel agencies is the same.

3) Set the number of people to x

When travel agency A or travel agency B travels.

x<50

When travel agency A or travel agency B travels.

x=50 when travel agency A > travel agency B.

x>50

Answer: When x<50, A is cheaper.

When x=50, both are cheaper.

At x>50, B is cheaper.

1).When there are 30 students, the fee charged by travel agency A is 10 * 40 + 30 * 40 2 = 1000 yuan;

Travel agency B charges (10 + 30) * 40 * 60% = 960 yuan;

When the number of students is 70, the fee charged by travel agency A is 10 * 40 + 70 * 40 2 = 1800 yuan;

The fee of travel agency B is (10 + 70) * 40 * 60% = 1920 yuan;

2).If the number of students is x, the fees of the two travel agencies are equal, then there is.

10*40+40x 2=(10+x)*40*60%, so 400+20x=24x+240, so 4x=160, so x=40, that is, when the number of students is 40, the charges of 2 travel agencies are the same;

3).10*40+40x 2>(10+x)*40*60%, x<40, that is, when the number of students is less than 40, it is cost-effective to choose travel agency B;

10*40+40x 2<(10+x)*40*60%, x>40, that is, when the number of students is greater than 40, it is cost-effective to choose travel agency A;

When the number of students is 40, it is equally cost-effective for 2 travel agencies.

1) 30 people: A: 10 * 40 + 30 * 40 * yuan) B: (10 + 30) * 40 * yuan).

70 people: A: 10*40+70*40*yuan).

B: (10+70)*40*yuan).

2) If the number of students is x, the charges will be the same for both travel agencies.

then 10*40+40x*

400+20x=240+24x

4x=160

x=40 So when the number of students is 40, the charges are the same for both travel agencies.

3) If the number of students is more than 40, it is cost-effective to choose Travel Agency B;

If the number of students is equal to 40, the price of the two travel agencies is the same, and it is cost-effective;

If the number of students is less than 40, it is cost-effective to choose A travel agency.

Be lazy, hehe

Question 1: When there are 30 students, the fee of Company A is 10x40 + 30x20 = 1000 yuan; The fee of company B is 40 (person) x 40 (yuan person) x 60% = 960 yuan; When the number of students is 70, the fee of company A is 10x40 + 70x20 = 1800 yuan, and the fee of company B is 80 (person) x 40 (yuan person) x 60% = 1920 yuan.

Question 2: If the number of students is x, the fee is the same, and the equation is obtained:

10*40+x*20=(x+10)*40*60%400+20x=240+24x

x=40 Question 3: Let's do it yourself, hehe.

First, if student 0 A 10·40 + 30·20 = 1000 B 40·60 ·40 = 960

If there are 0 students, A 10·40+70·20=1800 B, 80·40·60 =1920

Second. When there are x number of students.

10·40+x·20=(10+x)·40·60 Solve the equation porphy with curcuma.

Third. Find the second x.

If it is greater than the value of the second question, it is worth it.

Less than the opposite.

over

In order to get rich and well-off, farmer Uncle Zhang vigorously developed the family breeding industry, he was ready to use a 40-meter-long wooden fence to enclose a rectangular breeding circle, in order to save materials, and at the same time to make the rectangular area the largest, he used a 25-meter-long wall of his house, designed a rectangular breeding circle as shown in the figure

1) Please find the area of the rectangular sheepfold designed by Uncle Zhang;

2) Can you judge if his design maximizes the area of the rectangular sheepfold? If it's not the largest, how should it be designed? Please explain the reason Test point: Application of quadratic functions Topic: Application questions Analysis: (1) The number of sheepfolds designed by Uncle Zhang.

Answer: 1Set from A to X to B.

By the inscription: 22+x=2(38-x).

Solution: x=18

Therefore, 18 people should be transferred from A to B.

2.Analysis: Let the age of the sister be x, and the age of the sister is y, and the meaning of the question: x+4=2y

x = from the above equations: x = 12, y = 8

So Sister Zenzi is 12 years old this year.

3.Analysis: Set the single digit to x and the ten digit to y

From the title: x+y=10

10y+x+36=10x+y

Solving the system of equations yields x=7, y=3

So the original two-digit number was Qingran 37

If you have any difficulties, we will be happy to help!

1 According to the topic, if how many people should be transferred from A to B x people, then there is 2(38-x) = (22 + x) to get x = 18

2. Set the younger sister to be x years old and the sister to be y years old this year. According to the meaning of the title, there is 2(x-4)=y-4 to get x=8y=12

My sister is 12 years old.

3 The original 2-digit number of Sanxiang is 37

This question can be enumerated; You can also set the original 2 digits to xy, then there are no cherry blossoms, x+y=10

yx=xy+36

y+6=1x

x+3+1=y∴x=3y=7

1. Set the purchase price to x

Interest rate = (ask price - purchase price) Purchase price 2 set the distance traveled by the teacher is xThe final distance is more than 3km as you know from the title

3 + (3 by the question of one degree of elevation, A is less than B, 27 kWh, electricity A-B = 27, B = 27 + A to B, after cleaning the equipment, B = (27 + A) multiplied by 11 to get A.

Let the purchase price be x, then the solution is x=21

If the distance traveled is x kilometers, then there is 8+(x-8)*, which gives x=16

Solution: (1) According to the conditions: 90 kg of lubricating oil for processing a large machinery and equipment, and the reuse rate of oil is 60

So the actual amount of oil consumed in processing a machine is:

Total oil volume Reusable oil volume 90 90*60% 36 (kg) The remaining 54 kg is reusable.

Therefore, in the case of "after the renovation of workshop A, the amount of oil used to process a large lubrication has been reduced to 70 kg, and the repetition rate of oil is 60%".

The actual fuel consumption is: 70 70 * 60% 28 (kg) (2) The amount of oil used is reduced by x kg, so the oil consumption is 90 x kg according to the "oil consumption decreases by 1 kg, and the reuse rate increases:

The reuse rate of the oil is (60, so the equation is obtained.

90－x)*[1－(60＋

x－90)*(x－25)＝750

x 2 115x 1500 0, solution x 100 or x 15, obviously x 100 is not on topic.

So x 15

Therefore, the amount of oil used is 75 kg, and the reuse rate of oil is 15*In addition, (2) can also be solved as follows:

Set up workshop B to process a large mechanical equipment lubrication oil of y kilograms from the title.

y*[1－(90－y)*

Sorted out to get y 2 65 y 750 0

Solution: y1 75, y2 10 (rounded).

So: (90 75)*

FYI! jswyc

1.Nanchang, Wuhan.

Wenzhou 6-x 4+x

Hangzhou x 4-x

Therefore, after multiplying and simplifying the corresponding fare, we get 7600+200x yuan, where 0<=x<=4

2. x=4

3.7400 is clearly impossible.

This is a first-class ratio series with a ratio of -2

Let the first of the three adjacent numbers be x

The three numbers are x -2x 4x

x-2x+4x=384

x = 128, these three numbers are 128 -256 512

Solution: Set the purchase ** to x, and the total pre-sale price to y

Solution: x=4400

y=8000

Note: If there is an error in the data, it should be an error in the profit of the discount, otherwise the result of the solution will be negative, and the above result can be obtained by changing 8000 to 800, and the process is correct.

Solution: Set the purchase ** to x, and the total pre-sale price to y

Solution: x=4400

y=8000

Set the unit price to x and the purchase ** to y