The ratio of ages of father and the son at present is 5:After 12 years the ratio will become 3:What is the sum of present ages of the father and the son ?

The correct answer is (d) 72 yrs.

Let the present ages of the father and the son be 5x and x years respectively.
After 12 years, their ages will be (5x+12) and (x+12) years respectively.
Given that the ratio of their ages after 12 years will be 3:2.
Therefore,
(5x+12)/(x+12) = 3/2
10x+24 = 3x+36
7x = 12
x = 12/7
Therefore, the sum of their present ages is
5x + x = 6x = 6 * 12/7 = 72 yrs.