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# John is 20 years older than Brian. 12 years ago, John was twice as old

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Re: John is 20 years older than Brian. 12 years ago, John was twice as old [#permalink]
12 years ago:
Let Brian from 12 years ago equal X.

John = 2X

NOW:
Brian = X+12
John = 2X+12 OR X+12+20

Let 2X+12 = X+12+20
Thus X = 20

Substitute back into the equation:
Brian now: 20+12=32

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John is 20 years older than Brian. 12 years ago, John was twice as old [#permalink]

J = 20 + B

J - 12 = 2 ( B - 12 )

Putting value of ' J '

20 + B - 12 = 2B - 24

8 + B = 2B - 24

B = 32
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Re: John is 20 years older than Brian. 12 years ago, John was twice as old [#permalink]
John is 20 years older than Brian => John = Brian + 20 ---------------(1)

12 years ago, John was twice as old as Brian => (John - 12) = 2 (Brian - 12)

=> John - 12 = 2 Brian - 24

=> John = 2 Brian -12 ---------------(2)

From (1) and (2),

=> Brian + 20 = 2 Brian - 12

=> 20 + 12 = Brian

=> Brian = 32

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Re: John is 20 years older than Brian. 12 years ago, John was twice as old [#permalink]
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Re: John is 20 years older than Brian. 12 years ago, John was twice as old [#permalink]
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