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Re: Two years ago, Cecilia's mother was three times as old as Cecilia. In [#permalink]
generis wrote:
Bunuel wrote:
Two years ago, Cecilia's mother was three times as old as Cecilia. In 12 years, Cecilia's mother will be twice as old as Cecilia. How old is Cecilia currently?

A. 10
B. 12
C. 14
D. 16
E. 18

C = Cecilia
M = Mother

Two years ago:
C's mother was three times as old as C
M - 2 = 3(C - 2)
M - 2 = 3C - 6
M = 3C - 4 ---> Use this for next equation

In 12 years:
C's mother will be twice as old as C
M + 12 = 2(C + 12) - substitute
(3C - 4) + 12 = 2C + 24
C = 16

Answer D



Hello generis, can you advice if my approach is correct :)

C = Cecilia
M = Mother

m=3c-2 <---- Two years ago, Cecilia's mother was three times as old as Cecilia
m=12+2c < ---- In 12 years, Cecilia's mother will be twice as old as Cecilia

How old is Cecilia currently? <--- C ? :)

3c-2 = 12+2c
3c-2c = 12+2
c= 14

Since two years ago, Cecilia's mother was three times as old as Cecilia - 2, so we add those two years to 14 and get 16 :) no ? :? I think I missed something though I answered correctly :)
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Re: Two years ago, Cecilia's mother was three times as old as Cecilia. In [#permalink]
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dave13 wrote:
Bunuel wrote:
Two years ago, Cecilia's mother was three times as old as Cecilia. In 12 years, Cecilia's mother will be twice as old as Cecilia. How old is Cecilia currently?

A. 10
B. 12
C. 14
D. 16
E. 18

Hello generis, can you advice if my approach is correct :)

C = Cecilia
M = Mother

m=3c-2 <---- Two years ago, Cecilia's mother was three times as old as Cecilia
m=12+2c < ---- In 12 years, Cecilia's mother will be twice as old as Cecilia

How old is Cecilia currently? <--- C ? :)

3c-2 = 12+2c
3c-2c = 12+2
c= 14

Since two years ago, Cecilia's mother was three times as old as Cecilia - 2, so we add those two years to 14 and get 16 :) no ? :? I think I missed something though I answered correctly :)

dave13 , you're not missing anything. You did one step in your head (adding 2 at the end). I think that's what you're sensing.

You and kablayi (welcome!) used similar approaches with variables defined a bit differently.

You just didn't "remind" yourself explicitly -- as kablayi did by writing Cecilia's age "now" as "x + 2" -- that whatever you calculated for Cecilia's age would require you to add 2.

In short, good instincts! :-)
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Re: Two years ago, Cecilia's mother was three times as old as Cecilia. In [#permalink]
M = Cecilia's mother
C = Cecilia

Two years ago:
(M - 2) = 3(C - 2)
Simplifying the equation, M - 3C = -4 Equation 1

In twelve years:
(M + 12) = 2(C + 12)
Simplifying the equation, M - 2C = 12 Equation 2

Subtracting Equation 1 from Equation 2,
M - 2C = 12
- M - 3C = -4
C = 16. Hence Cecilia is currently 16 years old (Option D)
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Re: Two years ago, Cecilia's mother was three times as old as Cecilia. In [#permalink]
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Current age of Cecilia = y and current age of Cecilia's mother = y

According to given statements :

x-2 = 3y & x+12 = 2(y+12)

Solving y =10
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Re: Two years ago, Cecilia's mother was three times as old as Cecilia. In [#permalink]
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Re: Two years ago, Cecilia's mother was three times as old as Cecilia. In [#permalink]
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