SOLUTION: Mike's son John is exactly one fifth of Mike's age. In 21years time, Mike will be exactly twice John's age. How old is John now?

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Question 1039637: Mike's son John is exactly one fifth of Mike's age. In 21years time, Mike will be exactly twice John's age. How old is John now?
Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
J = 1/5M
M+21 = 2(J+21)
M+21 = 2(1/5M+21)
M+21 = 2/5M+42
M = 2/5M + 21
M-2/5M = 21
3/5M = 21
M = 21(5/3) = 105/3 = 35 Mike is 35 years old and John is 1/5(35) = 7 years old.