SOLUTION: A father is now three times as old a son,12 years ago he was 6 time as old as a son.find their present ages.

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Question 789380: A father is now three times as old a son,12 years ago he was 6 time as old as a son.find their present ages.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +f+ = father's age now
Let +s+ = son's age now
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(1) +f+=+3s+
(2) +f+-+12+=+6%2A%28+s+-+12+%29+
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Substitute (1) into (2)
(2) +3s+-+12+=+6%2A%28+s+-+12+%29+
(2) +3s+-+12+=+6s+-+72+
(2) +3s+=+60+
(2) +s+=+20+
and, since
(1) +f+=+3s+
(1) +f+=+3%2A20+
(1) +f+=+60+
--------------
The father is 60 and the son is 20
check:
(2) +f+-+12+=+6%2A%28+s+-+12+%29+
(2) +60+-+12+=+6%2A%28+20+-+12+%29+
(2) +48+=+6%2A8+
(2) +48+=+48+
OK