The age of the father is 30 years more than the son's age. Ten years hence, the father's age will become three times the son' age that time. What is the son's present age in years?

Options

A. Eight
B. Seven
C. Five
D. Cannot be determined

Explanation

Let the son's present age be x years. Then the father's present age is (x + 30) years.
Father's age after 10 years = (x + 40) years
Son's age afater 10 years = (x+10) years
` (x+ 40) = 3 (x+10)`
` x + 40 = 3x + 30`
` 2x = 10`
` :. x = 5`