If the father is 60, the son is 30 (half the age).
From here, we can tell that father's age= son's age+30. We can now create the system of equations as follows.
f= s+30
f=4s
Because both define f, put the two equations together.
4s=s+30
3s=30
s=10
Final answer: The boy was 10 (and his father was 40).
