Answer: Brandon is 24, Michael is 72.
Explanation:
Let m represent Michael
Let b represent Brandon
Then,
m = 3b <-----------"Michael is 3 times as old as Brandon."
m - 18 = 9(b - 18) <-----------"18 years ago, Michael was 9 times as old as Brandon."
3b - 18 = 9b - 162
-18 = 6b - 162
144 = 6b
Michael is 3 times as old as Brandon. Also, 18 years ago, Brandon would have been 6 and Michael would have been 54 meaning Michael was 9 times as old as Brandon 18 years ago.