SOLUTION: 12 years ago the age of a brother was four times that of the other. Knowing that the oldest was 27 when the child was born, what is the current age of both now.

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Question 471106: 12 years ago the age of a brother was four times that of the other.
Knowing that the oldest was 27 when the child was born, what is the current age of both now.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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12 years ago the age of a brother was four times that of the other.
Knowing that the oldest was 27 when the child was born, what is the current age of both now.
:
Let a = older brother's present age
Let b = younger brother present age
:
"12 years ago the age of a brother was four times that of the other."
a - 12 = 4(b - 12)
a - 12 = 4b - 48
a = 4b - 48 + 12
a = 4b - 36
:
"Knowing that the oldest was 27 when the child was born,"
a = b + 27
replace a with (4b-36)
4b - 36 = b + 27
4b - b = 27 + 36
3b = 63
b = 63%2F3
b = 21 yrs, younger brother's present age
then
a = 21 + 27
a = 48 yrs, older brother's present age
:
:
Check solutions in the statement:
"12 years ago the age of a brother was four times that of the other."
48 - 12 = 4(21 - 12)
36 = 4(9)