Question

Sam is 5 years old. His older brother, Tom, is three times as old as Sam. When Sam is 20, how old will Tom be?

Answer 1

Sam is 5
Tom is 3 times older so 3*5=15
The difference between them is 15-5=10 years
When Sam is 20 we add the difference 20+10=30, and we have Tom's age :)