SOLUTION: Frank is 15 years younger then John. In 5 years John will be twice as old as Frank. How old will Frank be in four years?

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Question 763535: Frank is 15 years younger then John. In 5 years John will be twice as old as Frank. How old will Frank be in four years?
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
Frank is 15 years younger then John. 
F = J - 15

In 5 years John will be twice as old as Frank.
J + 5 = 2(F + 5)

That gives us this system of equations:

F = J - 15
J + 5 = 2(F + 5)

We solve that and get

F = 10, J = 25

How old will Frank be in four years?
What is F + 4 ?

F + 4 = 10 + 4 = 14.

Edwin