SOLUTION: A father is twice as old as son now. If father is 5/3 times the age of son after 10 years, find their present ages.

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Question 697276: A father is twice as old as son now. If father is 5/3 times the age of son after 10 years, 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
+f+%2B+10+ = Father's age in 10 years
+s+%2B+10+ = Son's age in 10 years
given:
(1) +f+=+2s+
(2) +f+%2B+10+=+%285%2F3%29%2A%28+s+%2B+10+%29+
----------------------------
(2) +f+%2B+10+=+%285%2F3%29%2As+%2B+50%2F3+
Substitute (1) into (2)
(2) +2s+%2B+10+=+%285%2F3%29%2As+%2B+50%2F3+
(2) +6s+%2B+30+=+5s+%2B+50+
(2) +s+=+50+-+30+
(2) +s+=+20+
and, since,
(1) +f+=+2s+
(1) +f+=+2%2A20+
(1) +f+=+40+
The Father is 40 and
The Son is 20
-------------
check:
(2) +f+%2B+10+=+%285%2F3%29%2A%28+s+%2B+10+%29+
(2) +40+%2B+10+=+%285%2F3%29%2A%28+20+%2B+10+%29+
(2) +50+=+%285%2F3%29%2A30+
(2) +50+=+50+
OK