Question 167513: Anna made the following announcement:
In 7 years, I will be half my mother's age. Thirteen years ago, she was 6 times as old as i was then.
How old is Anna now?
Found 2 solutions by stanbon, nerdybill:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Anna made the following announcement:
In 7 years, I will be half my mother's age. Thirteen years ago, she was 6 times as old as i was then.
How old is Anna now?
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Let anna be x yrs old now.
Let mother be y yrs old now.
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EQUATIONS:
x+7 = (1/2)(y+7)
Y-13 = 6(x-13)
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Rearrange to solve:
2x - y = -7
6x -y = -7*-13
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Subtract 1st equation from 2nd to get:
4x = -7*-14
x= 24.5 yrs old now (Anna's age now)
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Cheers,
Stan H.
Answer by nerdybill(7384)  (Show Source):
You can put this solution on YOUR website! In 7 years, I will be half my mother's age. Thirteen years ago, she was 6 times as old as i was then.
.
Let A = Anna's age
and M = Mother's age
.
From:"In 7 years, I will be half my mother's age"
A+7 = M/2 (equation 1)
.
From:"Thirteen years ago, she was 6 times as old as i was then"
6(A-13) = M (equation 2)
.
Using the definition of M from equation 2, substitute it into equation 1 and solve for A:
A+7 = M/2
A+7 = (6(A-13))/2
A+7 = 3(A-13)
A+7 = 3A - 39
7 = 2A - 39
46 = 2A
23 years = A
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