Karthik is now 32 years old and his son is 7 years old. In how many years will Karthik be twice as old as the son?

Given Karthik’s age = 32 years

Karthik’s son age = 7 years

Difference between their ages = K - S = 32 - 7 = 25 years ….(1)

Now, required K = 2S ……(2)

Put (2) in (1)

2S - S = 25

=> S = 25 years

Hence, at the age of 25 years of Karthik’s son, Karthik will be twice as his son’s age.

25 - 7 = 18 years

Therefore, after 18 years the father be twice as old as the son.