There are 3600 science and technology books in the store, and the number of literature and art books is 5 / 9 of that of science and technology books?

There are 3600 science and technology books in the store, and the number of literature and art books is 5 / 9 of that of science and technology books?

3600 * 5 / 9 = 2000

There are 720 more literature and art books than science and technology books, and the number of literature and art books is four times that of science and technology books

I don't know what grade you are in now, so do it both in one and two ways
Univariate equation:
If there are x science and technology books and 4x literature and art books
4X-X=720
X = 240 (copies)
4X = 960
A: there are 960 literature and art books
If there are x literary and art books, X / 4 science and technology books
X-X/4=720
The result shows that x = 960
A: there are 960 literature and art books
Binary equation:
There are x literature and art books and Y science and technology books
X-Y=720
X=4Y
The result shows that x = 960
Y = 240
A: there are 960 literature and art books

A total of 240 packages of science and art books came from the bookstore, accounting for one sixth of them. Later, a batch of scientific and technological books came in At this time, there are two kinds of science and technology books in total?

Literature and art books: 240 × (1-1 / 6) = 200 (package)
Science and technology book: 200 × (1-3 / 11) - 200 = 75 (package)

The number of science and technology books transported into bookstores is 5 / 7 of that of literature and art books. When one fifth of science and technology books are sold, the remaining science and technology books are 1200 less than the literature and art books. How many scientific and technological books are transported in

When a fifth of science and technology books are sold, the rest are literature and art books
5 of 7 × (1-5) = 4 of 7
Literature and art books
1200 ÷ (4 / 1-7) = 2800 (Ben)
Bring in science and technology books
2800 × 5 / 7 = 2000 (copies)

In bookstores, science and technology books account for four fifths. If we replace 20 science and technology books with literature and art books, we will have 8 out of 15 science and technology books. How many science and technology books are there

According to the meaning of the title,
The total number of science and technology books will remain unchanged when 20 science and technology books are replaced by literature and art books;
The proportion of science and technology books in total books has changed from 4 / 5 to 8 / 15,
So, 20 books account for 4 / 5-8 / 15 = 4 / 15
The total number of books is 20 / (4 / 15) = 75,
Original 75 * 4 / 5 = 60 science and technology books

The number of science and technology books in the school library is four times that of literature and art books, and there are 360 more scientific and technological books than literature and art books?

Science and technology books are four times as many as literature and art books, and there are three times more science and technology books than literature and art books
There are 120 literature and art books and 480 science and technology books
Equation: suppose there are x literature books and 4x science and technology books
So: 4x-x = 360, 3x = 360, x = 120
There are 120 literature and art books and 480 science and technology books

One fourth of the number of literature and art books in the school reading room is equivalent to two fifths of the number of science and technology books. There are 120 more literature and art books than science and technology books. How many books are there in each?

Literature and art books: Science and technology books
=2/5：1/4
=8：5
Literature and art books = 120 × (8-5) × 8 = 320 copies
Science and technology books = 320-120 = 200
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There are 456 literature and art books and science and technology books in the library of the school. 40% of the literature and art books are lent out. After 24 science and technology books are purchased, the number of the two books is the same. How many original literature and art books are there?

There were originally x literary books
x﹙1－40%﹚＝456－x＋24
8x/5 ＝480
x＝300
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The school library purchased 1050 books, one sixth of the number of literature and art books is equal to one ninth of science and technology. How many books are each?

Literature and art books: Science and technology books = 6:9
Literature and art books = 1050 × (6 + 9) × 6 = 420 copies
Science and technology books = 1050-420 = 630 copies

There are 180 reference books and 1. 2% science and technology books 3. The number of literary and artistic books is one of the other two books 5. How many books have been purchased?

One
5+1=1
6；
180÷（1-1
3-1
6），
=180÷1
2，
=360 (copies);
A: a total of 360 books have been purchased