Question 980379: A father is 60 years old and his son is half his age. How old was the boy when his father was four times his age? Answer by macston(5194) (Show Source):
You can put this solution on YOUR website! .
F=father's age; S=son's age; x=years ago father's age=4 times son's age
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F=2S
60=2S
30=S Son is 30 years old.
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F-x=4(S-x)
60-x=4(30-x)
60-x=120-4x
3x=60
x=20 Father was 4 times as old as son 20 years ago.
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Son is now 30, 20 years ago he was 30-20=10 years old.
ANSWER: The son was 10 years old when his father was four times his age.
(Father is now 60, so Father was 60-20=40 years old.)
