Answer:
30 Chocolates
Explanation:
The box was new and therefore full, so it had 5/5 of chocolates left.
When Bob ate 18, 2/5 were left, so he must have eaten 5/5 - 2/5 or 3/5 of the chocolates:
5/5 - 2/5 = 3/5
You know that 3/5 of the chocolates are 18, as he ate 18 chocolates. Divide 18 by 3 to get 6:
18 / 3 = 6
This is 1/5 of the chocolates. Multiply this by 5 to get 30:
6 * 5 = 30
This is 5/5 of the chocolates and therefore the total is 30 chocolates.