Explanation
Let's find the smallest number of apples that can be divided among 15, 10, and 20 children:
Multiples of 15: 15, 30, 45, 60, ...
Multiples of 10: 10, 20, 30, 40, 50, 60, ...
Multiples of 20: 20, 40, 60, ...
Find the smallest number that appears in all three lists: 60
The correct answer is: 60