The ratio of the present age of father to that of his son is 7: 2. If after 10 years the ratio of their ages will become 9: 4, then the present age of the father is:

35 years

ATQ,

Lets assume, present age of father is 7x and son is 2x

Given, after 10 years ratio of their ages ⇒ \(\frac{7x + 10}{2x + 10}\) = \(\frac{9}{4}\)

                                                         ⇒ 28x + 40 = 18x + 90

                                                         ⇒ x = 5

Present age of father = 35 years