12 year old Manish is three times as old as his brother Rajeev. How old will Manish be when he is twice as old as Rajeev ?

12 year old Manish is three times as old as his brother Rajeev who must be 4 years old.
Diff in ages = 8 years.
when Rajeev will become 8 years old, Manish will be 16 yrs old and he will be twice as old as Rajeev.