V : Ravi's age
N : Ranu's age
V = 2N
V + N = 72
Input the "V = 2N" into "V + N = 72"
2N + N = 72
Add like terms.
3N = 72
Divide.
N = 24 yrs.
Input N in "V = 2N"
V = 2 ( 24 )
Multiply.
V = 48 yrs.
Ravi is 48 years old and Ranu is 24 years old.
Hope this helped! Good luck! :D