How to do this question? Please do not use equations, but write down the calculation process.

Total number of books in the library = 520 + story books can also = 500 + science books.

Twice the total number of books in the library = 520 + story books + 500 + science books.

Twice the total number of books in the library = 520 + 500 + story books + science books.

Storybook + Science Book = 700 copies.

Twice the total number of books in the library = 520 + 500 + 700.

Twice the total number of books in the library = 1,720.

Total number of books in the library = 1720 2 = 860.

There are 520 books that are not storybooks and 500 books that are not science books, indicating that there are 20 fewer stories than science books.

There are 700 storybooks and science books, so there are (700-20) 2,340 storybooks.

There are 520 books that are not storybooks, so there are 340 + 520 860 books in total.

Except for story books and science books, the number of books (520+500-700) 2=160.

There are a total of 160 + 700 = 860 copies.

520 500 700 320 (Ben).

320 2 160 (Ben).

700 160 860 (book) Note: 520 500 represents a story book and a science book plus other books, but the other books are counted twice, so the next formula divides by 2 to get its book

If Xiaoli has x, then Xiaoliang has 2x.

2x－3＝x＋3

x 6 Xiaoli has 6 and Xiaoliang has 12.

Solution: There are x Xiaoli. 2x-x=3 2 x=6 6 2=12 (pcs) Answer: Xiaoli has a 6, Xiaoliang has a 12.

Set x hours to gather 20 kilometers.

Then the equation can be listed: (25+15)x+20=140, and x=3, so it is three hours.

4（2x—5k）—2=—（x—7k）

8x-20k-2=-x+7k

27k=7x-2

k=(7x-2)/x

5（x-9）>=15—6（x-1)--1)1/5x—2<=4—2/5x---2)

From (1): 5x-45>=15-6x+1

11x>=61

x>=61/11

From (2): x 5-2< = 4-2x 5

3x/5<=6

x<=10

Namely. 61/11<=x<=10

2x+3yz=11

2x+y—5z=8

2x+7y+z=19

1)-(2)get:2y+4z=3

2) + (3) yields: 8y-4z=27

4) + (5) gets: 10y=30

y=3 and y=10 into (4).

z=-3/4

Substitution (1) code defeat: x=5 8

Establish. His sluggish throbbing.

Plane ticket. It's x-yuan.

30-20)x*

The two specifications of long rice and rice are x, (100-x) respectively.

<> picture: Qing banquet, cherry blossoms, and auspicious hail.

Such as hail Dan nuclear knowledge of the source of the disturbance.

<> Shen Zheng patted the celebration exam and shouted Zhixian.

If the younger brother has x stamps, then the sister has 4x, and according to the title, x+4x=225

5x=225

x=225÷5

x=454x=4×45=180

A: My brother has 45 and my sister has 180.

There are x stamps for the younger brother.

x+4x=225

5x=225

x=225÷5

x = 45 pieces.

Sister has: 45x4 = 180 pieces.

Suppose the younger brother has x stamps, 4x+x=225, 5x=225, x=225 5, x=45, 4x=45 4=180, the younger brother has 45, and the elder sister has 180.

Let the younger brother have x pieces.

4x+x=225

x=454 45=180 (pieces).

A: My sister and brother have 180 and 45 respectively.

If Xiao Li walks x kilometers per hour, then Xiao Wang rides for two hours and Xiao Li walks for 2 + 1 = 3 hours. So there is 3x+2*15=, i.e. 3x=, x=.