Question

On Chris's birthday in 1992, he was half the age of his brother Joseph. On Chris' birthday in 1998, he was two-thirds the age of Joseph. How old will Chris be on his birthday in 2018?

Answer 1

Suppose in 1992 Chris was x years old, his brother was then 2x years old.
6 years later in 1998, Chris is (x+6) years old, his brother is (2x+6), 
(x+6)=(2/3)(2x+6)
x+6=(4/3)x+4
(4/3)x-x=6-4
(1/3)x=3
x=6
in 1992, Chris was 6, so in 2018 he will be 6+(2018-1992)=32 years old.