Math problem: The school distributed a batch of books to the first, second, third and third grades according to the ratio of 2: 3: 5, and the third grade got 120. How many books were distributed to the first and second grades? Analysis: According to the ratio of 2: 3: 5, it is allocated to the first, second, third and third grades, and the third grade is allocated to 120 books.

Explain that the third grade 120 is 5 copies, and each copy is 120÷5=24 copies.

The first grade is 24×2=48 books.

Grade two is 24×3=72 books.