I am anxious for the answer to the question of the proportion of the sixth grade of primary school,

If there are 3x people in school A and 5x people in school B, then: (3x-150):(5x+150)=3:7

Get: x=250

3x=750,5x=1250

Originally, there were 750 students in School A and 1,250 students in School B.

If the original number of students in school A is x, then the number of students in school B is 5 3xx-150) (5 3x+150)=3 7x=750 (people).

The original number of students in school B: 5 3 * 750 = 1250 (people).

Analysis: There was no change in the total number of students in the two schools before and after the change. Before the change, school A accounted for 3 (3+5)=3 8 of the total number of students, and school B accounted for 5 (3+5)=5 8

After the change, school A accounts for 3 (3+7)=3 10(1) The total number of people is 150 (3 8-3 10) = 2000. (2) The original school A is 2000*3 8=750 students.

3) The original school B is 2000*5 8=1250 students.

Originally, School A and School B had 3x and 5x students respectively.

3x-150）：(5x+150)=3:7

x=250a: 250*3=750

Number of students in school B: 250*5=1250

A: X people B: Y people.

x：y=3：5

x-150）:(y+150)=3：7

The solution is x=750 and y=1250

Let school A be originally x person, then B small will be (5 3)x, and there is a proportional relationship between x, which is: (x-150): [5 3) x+150] = 3:7

It turns out that the original number of students in school A was 750 and that of school B was 1250

If school A is originally x people, then B elementary school is (5 3) x

There is a proportional relationship between them, which is: (x-150): [5 3) x+150] = 3:7

It turns out that the original number of students in school A was 750 and that of school B was 1250

(This is the actual cost of Wang Yu to buy the book.)

This is the actual cost of Li Xin to buy the book.

So this should be the money that Li Xin needs to pay Wang Yu, that is, yuan.

Then (Li Xin) should pay ( ) yuan to ( Wang Yu ) .

Press 2:3:4, a total of 9 copies, yuan, each share of yuan, so Wang out of the yuan, Zhang out of the yuan (just right), Li out of the yuan.

(1) Scale bar = distance on the map and distance from the field, 150km = 150x1000x100cm

Field distance = 2) 270kmx1 5000000 = convert 270km to cm, refer to the above 150km).

270km=27000000cm

27,000,000 multiplied by 1 part of 5 million =

Then you have to look at the scale of the original drawing.

It depends on the scale on the graph you measured, and the actual distance is calculated using the known scale.

Q3 output value: 100 (1+100 million yuan)Q1 output value: 100 (100 million yuan).

1. 120÷（1-40%）=200

20000-5000) (100%-30%)=10500 seems to be so, I didn't calculate it carefully.

1.Xiaohua has 200 books.

2.The book is 50 pages long.

3.There are also 10,500 unbound.

Solution: Set 12 gray magpies to protect x hectares of forest:: As a result, x this pair.

I think what you did should be right, I did the math, and the result is the same as you: the number of hectares, 10,000 is the number of insects, it is the number of hectares of forest that can be protected for every 10,000 insects eaten, x is the number of hectares, and 10,000 is the number of insects, so that the equation is formed, if you use 12, 12 is the number of magpies, the calculation should be the forest that each magpie protects in a year, and it calculates the forest that can be protected for every 10,000 insects eaten. (By the way, I'm also in the sixth grade, so I'm under a lot of pressure for exams).