Ratio of present ages of a father and son is 5 : 2 . After 4 years the ratio will become 2 : 1 . What is the difference in their present age ?

12 years

Ratio of →     father   :    son

                       5      :      2

Let the present age father  =  5x    &     present age of son = 2x

After 4 years ,

According to question ,

\(\frac{5x\;+\;4}{2x\;+\;4}\) = \(\frac{2}{1}\)

5x + 4 = 4x + 8

x= 4

Present age of father = 5x = 5 × 4 = 20

Present age of son = 2x = 2 × 4 = 8

Required difference = 20 - 8 = 12