Puzzle: How old is Lily?

PUZZLE: When Linda was 6 years old, her sister Lily was half her age. If Linda is 40.years old today, how old is Lily?

ANSWER AND EXPLANATION:

Lily is 37 years old!

When Linda is 6, Lily is 3 years old because Lucy is 3 years younger. So when Linda is 40, Lily must be 37!