SOLUTION: A father said to his son, When I was your age, you were 2 years old. His son replies, When I reach your age, you will be 68 years old. What is the father's present age?

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Question 1020663: A father said to his son, When I was your age, you were 2 years old. His son replies, When I reach your age, you will be 68 years old. What is the father's present age?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = the son's age now
Let +f+ = the father's age now
+f+-+s+ = the difference in their ages
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When the son was 2, the father was:
2 + [ the difference in their ages ]
+2+%2B+f+-+s+
That was when the father was
the son's present age, so
+s+=+2+%2B+f+-+s+
(1) +2s+-+f+=+2+
---------------
When the father is +68+,
then +68+ - [ the difference in their ages ] =
" your age " which is the father's present age, so
+f+=+68+-+%28+f+-+s+%29+
+f+=+68+-+f+%2B+s+
(2) +-s+%2B+2f+=+68+
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Multiply both sides of (1) by +2+ and add the equations
(1) +4s+-+2f+=+4+
(2) +-s+%2B+2f+=+68+
-------------------
+3s+=+72+
+s+=+24+
and
(1) +2s+-+f+=+2+
(1) +2%2A24+-+f+=+2+
(1) +f+=+48+-+2+
(1) +f+=+46+
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The father's present age is 46
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check:
The difference in their ages is: +46+-+24+=+22+
"A father said to his son, When I was your age,"
when the fathers was: +24+
" you were 2 years old."
+24+-+22+=+2+ OK
-----------------------
"When I reach your age, "
when the son is +46,
The father will be +46+%2B+22+=+68+ OK