Answer:

14 years old

Step-by-step explanation:

Let suppose that Raju age is X years old.

Raju father age = 3X +6

Now, Raju father age = 48 years old.

3X +6 = 48

3X=48-6=42 years old.

X = (42/3)=14 years old.

When the Raju father age is 48years old then Raju age is 14years old.