SOLUTION: The sum of ages of son and father 5 years ago was 46 years. after 8 years the father 's age will be twice the age of son. Find the present age of father

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Question 947559: The sum of ages of son and father 5 years ago was 46 years. after 8 years the father 's age will be twice the age of son. Find the present age of father
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = son's age now
Let +f+ = father's age now
---------------------------
(1) +s+-+5+%2B+f+-+5+=+46+
(2) +f+%2B+8+=+2%2A%28+s+%2B+8+%29+
---------------------------
(1) +f+%2B+s+=+46+%2B+10+
(1) +f+%2B+s+=+56+
and
(2) +f+%2B+8+=+2s+%2B+16+
(2) +f+-+2s+=+16+-+8+
(2) +f+-+2s+=+8+
-------------------
Subtract (2) from (1)
(1) +f+%2B+s+=+56+
(2) +-f+%2B+2s+=+-8+
---------------------
+3s+=+48+
+s+=+16+
and
(1) +f+%2B+s+=+56+
(1) +f+%2B+16+=+56+
(1) +f+=+40+
At present, the father is 40
check:
(2) +f+%2B+8+=+2%2A%28+s+%2B+8+%29+
(2) +40+%2B+8+=+2%2A%28+16+%2B+8+%29+
(2) +48+=+2%2A24+
(2) +48+=+48+
OK
(1) +f+%2B+s+=+56+
(1) +40+%2B+16+=+56+
(1) +56+=+56+
OK