X( 1- 1/5)= 53-X+ 19
If X= 40, A has 40 tons and B has 13 tons.
2. Literature books = 1200*(3/5)=720.
There used to be 480 science and technology books = 1200-720.
Let the newly bought science and technology book X be 720/(480+X)=4/3.
The solution is X=480. Now there are 480+X=960 science and technology books.
3. There are (1400-X) girls for every x boys.
X-(2/5 * X+ 10)= 1400-X-250
3/5 * X- 10 = 1 150-X
8/5*X= 1 160
If X=725, there are 725 boys and 675 girls.