SOLUTION: A father, being asked his age and that of his son, said, "If you add 4 to my age and divide the sum by 4, you will have my son's age. But 6 years ago I was 7 1/2 times as old as m

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Question 172631: A father, being asked his age and that of his son, said, "If you add 4 to my age and divide the sum by 4, you will have my son's age. But 6 years ago I was 7 1/2 times as old as my son." find their ages.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A father, being asked his age and that of his son, said,
"If you add 4 to my age and divide the sum by 4, you will have my son's age.
But 6 years ago I was 7 1/2 times as old as my son."
find their ages.
:
Let f = father's age now; s = son's age now
:
"If you add 4 to my age and divide the sum by 4, you will have my son's age."
%28%28f%2B4%29%29%2F4 = s
Multiply equation by 4
f + 4 = 4s
f = 4s - 4
:
"But 6 years ago I was 7 1/2 times as old as my son."
f - 6 = 7.5(s - 6)
f - 6 = 7.5s - 45
f = 7.5s - 45 + 6
f = 7.5s - 39
Substitute (4s-4) for f in the above equation
4s - 4 = 7.5s - 39
-4 + 39 = 7.5s - 4s
35 = 3.5s
s = 35%2F3.5
s = 10 yrs old is the son
then
f = 4(10) - 4
f = 36 yrs old is the father:
:
:
Check solution in the statement:
"If you add 4 to my age and divide the sum by 4, you will have my son's age."
%28%2836%2B4%29%29%2F4 = 10; confirms our solution


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