Four years ago a man was 6 times as old as his son. After 16 years he will be twice as old as his son. What is the present age of man and his son?

34,9

Let the present age of man be M years and his son be S years.

According to the question:

M - 4 = 6 (S - 4)

M - 4 = 6S - 24

M = 6S - 20 ------1st equation

M + 16 = 2(S + 16) 

M + 16 = 2S + 32 -------2nd equation

Putting (1) in the (2) equation

6S - 20 + 16 = 2S + 32

4S = 36

S = 9

M = 6S - 20 i.e. 54 - 20 = 34

So, the age of son is 9 years, and the age of father is 34 years