Let s take a look at this 6th grade math contest question, right?

1 There are three meadows, with an area of 5, 15, and 24 acres. The grass on the meadow is as thick and grows just as fast. The first plot of grass can feed 10 cows for 30 days, the second plot of grass can feed 28 cows for 45 days, Q: How many cows can eat for 80 days on the third plot?

2 Li Gang transported honeycomb coal to the military family Grandma Wang, the first time he transported all of it, and the second time he transported 50 pieces.

3. Dragon Net Games** stipulates: If you participate in game A continuously, you can get 47,000 points per month; Participate in Game B continuously and earn 35,000 points per month. In 2000, Xiao Ming participated in the Dragon Net game, first participating in Game A, and then participating in Game B a few months later.

With a total of 762,000 points at the end of the year, Xiao Ming began to participate in game A in last year ( ).

4A monkey picked a pile of peaches, and on the first day he ate them; The next day I ate the rest of the peaches; On the third day, he ate the rest of the peaches; On the fourth day, I ate the rest of the peaches; On the fifth day, he ate the rest of the peaches; If you eat the remaining peaches on the sixth day, there are 12 peaches left, so what is the total number of peaches eaten on the first and second days?

5 There are 11 liters of pure alcohol in container A, 15 liters of water in container B, pour a part of the pure alcohol in container A into container B for the first time, mix the alcohol with water, pour a part of the mixed solution in container B into container A for the second time, so that the pure alcohol content in container A is 62 5%, and the pure alcohol content in container B is 25%, and how many liters of mixed liquid is poured into container A from container B for the second time?

6 1, 2, 3, 3, 4, 4, 6, 2, 7, 8, 9 are all used, and how many different numbers can be formed.

Enter a few numbers at random, combine these numbers into a number, and output as many combinations as there are.

7 Grandpa Wang bought back a batch of apples at ** per kilogram of yuan, and after selection, this batch of apples was divided into two grades, such as A and B, and the weight ratio of A and B was 3:5;Grandpa Wang wants to get a profit of 25, how many yuan should first-class apples be sold for per kilogram?

You're not doing it right. The correct solution is as follows.

200 (1+25%) 160 trees.

160 5 8 = 100 trees.

100 60% 60 trees.

A: The 5th grade students actually planted 60 trees.

No, the original planned planting for the sixth grade: 200 (1+25%) 160 (trees).

There are a total of saplings: 160 (8 (5+8))=260 (trees).

Actual planting in the fifth grade: 260-200=60 (trees).

Because in the sixth grade of primary school, I only learned the one-dimensional one-dimensional equation, so I could only solve the above Olympiad numbers according to the one-dimensional one-dimensional equation.

So many of the above are also too stupid, and they should actually be solved like this:

Solution, assuming that you get the x question right, you get the wrong 20-x question.

So, there is: 5x-2*(20-x)=44

The solution is x=12

Answer: I got 12 questions right.

If all 12 are correct, then there should be 5 20 = 100 points;

He scored 44 points and lost 100-44=56 points;

If you start to reduce from the full score, you will lose 2 + 5 = 7 points if you make a mistake (not only will you not get the score but you will also be deducted), (if you don't do it, you will lose five points);

Because he did it all, it was either wrong or right, and there was only one case of losing 7 points.

That is, 56 7 = 8 wrong and 20-8 = 12 wrong.

Suppose you are clearly correct for a question x, not for y (because you have done every question, so it is not counted), and if you do a wrong question for z

A total of 20 questions!!

5x (the score of doing it right) - 2z (the score of doing it wrong) = 44x (the score of doing it right) + z (the score of the wrong question) = 20 (the total number of questions) The answer is as follows:

5x-2y=44

x+y=20

x=20-y

5(20-y)-2y=44

100-5y-2y=44

7y=-56

y=8x=y=20

y=8x=12

5 times 20 = 100 (points).

100-44 = 56 (points).

56 divided by (5+2)=8 (question).False 20-8=12 (question).Right.

Or set x questions correctly and y wrong questions.

5x-2y=44

x+y=20

x=20-y

5(20-y)-2y=44

100-5y-2y=44

7y=-56

y=8x=y=20

y=8x=12

Set x questions correctly and y wrong questions.

5x-2y=44

x+y=20

x=20-y

5(20-y)-2y=44

100-5y-2y=44

7y=-56

y=8x=y=20

y=8x=12

(1) Set the water gushing out of the well per minute is x, the pumping water per minute of each pumping machine is y, and the original water volume of the well is z, and n pumping machines are required.

Then there is: 3*y*36=36*x+z.........5*y*20=20*x+z………

, y=2x.........

In the same way, z=180x.........

There is also n*y*12=12*x+z, which brings in and solves n=8, so 8 pumping machines are needed.

2) 25 + 28 + 31-40 2 = 4 (people), you can draw a Wayne diagram to solve.

1. Set the efficiency of the pumping machine x, the amount of water gushing out per minute is y, and there is a system of equations 3·36x=1+36y, 5·20x=1+20y. To solve x,y, the number of pumping machines required is (1+12y) (12x

First, calculate the fraction of the total amount of three days, that is, the first day of the transformation (unified) unit 1: 1 3

Day 2: (1-1 3)*2 3=4 9

Day 3: 6 kg less than [(1 3 + 4 9) * 3 7] = 1 3 6 (1 3 + 4 9 + 1 3-1) = 54 (kg) 58-54 = 4 (kg).

"The eldest gave the rest of the brothers a half of the ......”

This sentence shows that the eldest invests one-third of the total number of brothers, and the second invests a similar ......

The total amount of capital contributed by the four people is X yuan.

The boss came out of the total 1 3

The second out of the total 1 4

The third out of the total 1 5

The fourth child has a total of 1-1 3-1 4-1 5=13 60 and the fourth child contributes 91,000 yuan, so (13 60) x = 91,000, and the total amount of capital contributed by the four people x = 420,000 yuan.

Hello dear....

This question is answered as follows: (Let the eldest contribute x yuan, the second child contributes y yuan, and the third child contributes z yuan, which is derived from the question: z (y+x+91000) y=1 3(z+x+91000) x= (91000+y+z) x=84000, y=105000, z=140000 of the joint solution of the above three equations, so the total investment is 329000 yuan).

The boss came out of the total 1 3

The second out of the total 1 4

The third out of the total 1 5

Therefore, the fourth child came out of 1-1 3-1 4-1 5=13 60, so a total of 420,000 was invested

The boss made a third of all (1 3).

The second out of all a quarter (1 4).

The third child made a fifth of all (1 5).

91,000 divided by 13 60 = 420,000

Set the eldest out of x, the second out of y, and the third out of z

x = 1/2 (y+z+91000).

y = 1/3 (z+x+91000).

z = 1/4 (x+y+91000).

Find x+y+z=

Observe the five equations of 1+3=4 4+5=9 9+7=16 16+9=25 25+11=36 and find out the law, then the next equation is (36+13=23).