SOLUTION: Rose is two third as old as Johnny. In 5 years, the sum of their ages will be 50 years. Find their present age.

The problem says

R =                   (1)   ("Rose is two third as old as Johnny.")

(R +5) + (J +5) = 50.      (2)    ("In 5 years, the sum of their ages will be 50 years.")



Simplify (2)

R + J = 50 -5 - 5,   or   R + J = 40   (3)



Now substitute (1) into equation (3).  You will get

 = 40.



Multiply by 3 both sides:

2J + 3J = 120  ====>  5J = 120  ====>  J =  = 24.



Answer.  Johnny is 24 years old.  Rose is   = 16 years old.