This age brain teaser is easy to get wrong if you assume the brother will always be half the other person’s age.
When I was 4 years old, my brother was half my age, so he was 2.
That means there is a 2-year age difference between us.
Age differences never change. If I am now 18 years old, my brother must still be 2 years younger:
18 − 2 = 16
The trick is remembering that the brother does not remain half the age forever.
Answer: My brother is 16 years old.


