5th grade math problem, please help solve the problem.

Assuming that all 7 classes are in the third grade, 20 7 = 140 kg can be collected, and each additional class is the 4th grade, and 5 kg more can be collected.

So the number of classes in Grade 4 is: (155-20 7) (25-20) = 3.

7-3 = 4 pcs.

A: ...

Solution: There are x classes in grade 3 and y classes in grade 4, and according to the meaning of the question, it can be known that 20x+25y=155

x+y=7 solves the system of equations to get:

x=4y=3 Therefore: 4 classes in the third grade and 3 classes in the fourth grade.

Solution: There are X classes in the third grade and each class in the fourth year.

x+y=720x+25y=155

The solution is x=4 y=3

There are x classes in the third grade and 7-x classes in the fourth grade.

20x+25（7-x）=155

Solution: x=4

i.e.: 7-x=3

A: There are 4 classes in the 3rd grade and 3 classes in the 4th grade.

There are x classes in the third grade, and since there are a total of 7 classes in the third and fourth grades, there are 7-x classes in the fourth grade, so.

20*x+25*(7-x)=155, solve the equation to get: x=4, then there are 7-4=3 classes in the fourth grade.

A: There are 4 classes in the third grade and 3 classes in the fourth grade.

If there are x classes in the third grade, then there will be (7-x) classes in the fourth grade.

Solution: x=4 7-x=3

A: There are 4 classes in the 3rd grade and 3 classes in the 4th grade.

Seven classes in the third and fourth grades collected 155 kg of tree seeds, with an average of 20 kg per class in the third grade and 25 kg per class in the fourth grade. 4 3

Is it an order or a fraction that is not exhaustive?

Just use a calculator to do the math, I can solve the equations.

24×3+2x=90

2x=18x=917×12-2x=17

2x=187

x=x=4x-2x=3×18

2x= 54

x=273x=x=

x=20x+4=13

x=94x-（

4x=12x=32x-56÷8=18

2x=25x=3x+48÷12=58

3x=54x=18

3x+3x=

x=41/6

x=15(x+

x+x=3x+2x+6=30

5x=24x=

It's so hard, I won't, because I'm only in the first grade of elementary school. But to tell you, you can click on the bottom left of the computer, all programs, accessories, calculators, etc

Are you lazy or won't do it yourself.

With a computer: Click Start and find all programs, accessories, computers.

Use the equation to set up: the fifth grade went to person x, then the fourth grade went to people.

x=120A: 144 people went to the fourth grade.

Solution: Suppose that the number of people going to the fifth grade is x, then the number of people going to the fourth grade is.

x+x=120 (person).

264-120=144 (person).

A: There were 144 people in the fourth grade.

5th grade 264 (1+).

4th grade 120*).

A: There were 144 people in the fourth grade.

Both the upper and middle decks have 10 rows of seats and a seat in each row.

That is: 10*2*a=20a

There are 16 rows on the lower level, and there are C seats in each row.

That is, 16*c = 16c

then the total is 20a+16c