The ratio of ages of the father and mother was 11:10, when their son was born. The ratio of ages of the father and mother will be 19  : 18, when the son will be 4 times of his present age. What will be the ratio of present age of father and mother?

13 : 12

When son was born: 

Father   :    Mother

 11        :     10

Let son's  present age = y years

Now, ATQ

\(\frac{11R + 4y}{10R + 4y}\) = \(\frac{19}{18}\)

⇒ 198R + 72y = 190R + 76y

⇒ 8R = 4y

⇒ y = 2R

Ratio of present age of Father and Mother:

⇒ \(\frac{11R + 2R}{10R + 2R}\) = \(\frac{13R}{12R}\) = 13 : 12