SOLUTION: 5 YEARS AGO A MAN 7 TIMES AS OLD AS HIS SON.AFTER 5 YEARS HE WILL BE THRICE AS OLD AS HIS SON.FIND THEIR PRESENT AGE

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Question 876577: 5 YEARS AGO A MAN 7 TIMES AS OLD AS HIS SON.AFTER 5 YEARS HE WILL BE THRICE AS OLD AS HIS SON.FIND THEIR PRESENT AGE
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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+f+-+5+ = father's age 5 yrs ago
+s+-+5+ = son's age 5 yrs ago
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+f+%2B+5+ = father's age in 5 yrs
+s+%2B+5+ = son's age in 5 yrs
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(1) +f+-+5+=+7%2A%28+s+-+5+%29+
(2) +f+%2B+5+=+3%2A%28+s+%2B+5+%29+
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(1) +f+-+5+=+7s+-+35+
(1) +7s+-+f+=+30+
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(2) +f+%2B+5+=+3s+%2B+15+
(2) +3s+-+f+=+-10+
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Subtract (2) from (1)
(1) +7s+-+f+=+30+
(2) +-3s+%2B+f+=+10+
+4s+=+40+
+s+=+10
and
(1) +f+-+5+=+7%2A%28+s+-+5+%29+
(1) +f+-+5+=+7%2A%28+10+-+5+%29+
(1) +f+-+5+=+7%2A5+
(1) +f+=+40+
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The father is 40 and the son is 10
This checks out if you read back
through the problem