SOLUTION: a son is half as old as his father.12 years ago the son was one third as old as his father. how is each now?

Question 319636: a son is half as old as his father.12 years ago the son was one third as old as his father. how is each now?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Let s = son's age
Let f = father's age
:
Write an equation for each statement
:
"a son is half as old as his father."
s = f
:
"12 years ago the son was one third as old as his father."
s - 12 = (f - 12)
multiply each side by 3, to get rid of the fraction
3(s - 12) = f - 12
3s - 36 = f - 12
3s = f - 12 + 36
3s = f + 24
Replace s with f, (from the 1st statement)
3(f) = f + 24
(f = f + 24
Multiply both sides by 2 to get rid of the fraction, results:
3f = 2(f + 24)
3f = 2f + 48
3f - 2f = 48
f = 48 yrs is father's present age
then
*48 = 24 yrs is son's present age
:
:
Check solutions in the statement
"12 years ago the son was one third as old as his father."
24 - 12 = (48 - 12)
12 = *36, confirms our solutions
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