3000 exercise books are arranged into 3 piles. The first pile has 10 more books than the second pile. The number of books in the second pike is twice the number of books in the third pile. How many books are there in the third pile.

598 books

Step-by-step explanation:

Let x be the number of books in the 3rd pile. We will have then:

1st pile: 2x + 10

2nd pile: 2x

3rd pile: x

3000 = (2x + 10) + (2x) + (x)

3000 = 5x + 10

3000 - 10 = 5x

2990 = 5x

2990/5 = x

x = 598 books in the third pile!

We can check that:

3000 = 2*598 + 10 + 2*598 + 598

3000 = 1196 + 10 + 1196 + 598

3000 = 3000 CHECK!