The ratio of the number of books obtained by Class Two and Class Three is 5 to 7.
1 class and class 2 get 2 to 3 books.
How many books are there in each class?
Answer: 1 class 90.
Category 2, 135 books
Class 3, 189
The process of solving problems
2x 5 = 10 3x 5 = 15 3x 7 = 2 1 10+ 15+2 1 = 46
4 14x 46 10 = 904 15 = 135 4 14x 46 2 1 = 189。