SOLUTION: the sum total of the ages of the son and his father is 58 years.if 7 years after the ratio of the ages of the son and father will be 1:3,then what is the age of son now?

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Question 1010120: the sum total of the ages of the son and his father is 58 years.if 7 years after the ratio of the ages of the son and father will be 1:3,then what is the age of son now?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = age of the son now
Let +f+ = age of the father now
----------------------------
(1) +s+%2B+f+=+58+
(2) +%28+s+%2B+7+%29+%2F+%28+f+%2B+7+%29+=+1%2F3+
----------------------------
(2) +3%2A%28+s+%2B+7+%29+=+f+%2B+7+
(2) +3s+%2B+21+=+f+%2B+7+
(2) +3s+-+f+=+-14+
--------------------
Add (1) and (2)
(1) +s+%2B+f+=+58+
(2) +3s+-+f+=+-14+
------------------
+4s+=+44+
+s+=+11+
The son is 11 now
------------------
check:
(1) 11+%2B+f+=+58+
(1) +f+=+47+
and
(2) +%28+s+%2B+7+%29+%2F+%28+f+%2B+7+%29+=+1%2F3+
(2) +%28+11+%2B+7+%29+%2F+%28+f+%2B+7+%29+=+1%2F3+
(2) +18+%2F+%28+f+%2B+7+%29+=+1%2F3+
(2) +3%2A18+=+f+%2B+7+
(2) +54+=+f+%2B+7+
(2) +f+=+47+
OK