SOLUTION: Five years ago, the age of the father was thrice the age of his son. In five years time, the age of father will be twice the age of his son at that time. Find their present ages.

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Question 592116: Five years ago, the age of the father was thrice the age of his son. In five years time, the age of father will be twice the age of his son at that time. 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
given:
(1) +f+-+5+=+3%2A%28+s+-+5+%29+
(2) +f+%2B+5+=+2%2A%28+s+%2B+5+%29+
--------------------
(1) +f+-+5+=+3s+-+15+
(1) +3s+-+f+=+10+
and
(2) +f+%2B+5+=+2s+%2B+10+
(2) +2s+-+f+=+-5+
Subtract (2) from (1)
(1) +3s+-+f+=+10+
(2) +-2s+%2B+f+=+5+
+s+=+15+
and
(1) +3s+-+f+=+10+
(1) +3%2A15+-+f+=+10+
(1) +45+-+f+=+10+
(1) +f+=+45+-+10+
(1) +f+=+35+
Father is 35 and Son is 15
check:
(1) +f+-+5+=+3%2A%28+s+-+5+%29+
(1) +35+-+5+=+3%2A%28+15+-+5+%29+
(1) +30+=+3%2A10+
(1) +30+=+30+
OK
(2) +f+%2B+5+=+2%2A%28+s+%2B+5+%29+
(2) +35+%2B+5+=+2%2A%28+15+%2B+5+%29+
(2) +40+=+2%2A20+
(2) +40+=+40+
OK