Question

A father is 4 times as old as his son. 5 years ago the sum of their age was 70. Find their present age.
Reiny
son's age --- x
father's age -- 4x

5 years ago:
son's age = x-5
father's age = 4x-5

x-5 + 4x-5 = 70

solve for x, plug into my definitions