The sum of present ages of a father and his son is 36 years. When the son reaches father’s present age, the sum of their ages will be 80 years. What is the present age of the son?
a) 4 years
b) 7 years
c) 9 years
d) 12 years
e) None of these
a) 4 years
b) 7 years
c) 9 years
d) 12 years
e) None of these