Mike’s age right now is exactly 3 times his age 3 years hence minus 3 times his age 3 years ago. How old is Mike right now?
Let m stand for Mike’s age. Then his age 3 years hence is m + 3, and his age 3 years ago is m – 3.
So: m = 3(m + 3) – 3(m – 3) = 3m + 9 – (3m – 9) = 3m + 9 – 3m + 9 = 18.
Check: If Mike is 18, then in 3 years he’ll be 21, and 3 years ago he was 15. So, does 18 equal 3 x 21 – 3 x 15 = 63 – 45 = 18? Yep.