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2014-11-25T18:44:39+08:00

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X-brother
carol-5x

5x=3(x+2)
5x=3x+6
2x=6
x=3

Therefore Carol is 15, her brother is 3.

Hope this helps =)
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2014-11-25T19:21:04+08:00
Let 'x' be the age of Carol's brother at present
      'y' be the age of Carol at present
 Two years from now:
    'x+2' --age of Carol's brother
    'y+2' ---Carol's age
-----------------------------------
-Carol is 5 times as old as her brother
y = 5x    ------equation 1
----------------------------------
-she will be three times as old as her brother in two years
(y+2) = 3(x+2)   
y + 2 = 3x + 6
y = 3x + 6 - 2
y = 3x + 4    -----equation 2
-----------------------------------
Substitute equation 1 to equation 2
y = 3x + 4
5x = 3x + 4
5x - 3x = 4
2x = 4
x = 2
----------------------------------
Substitute x=2 to equation 1
y = 5x
y = 5(2)
y = 10
---------------------------------
Therefore Carol is 10 years old and her brother is 2 years old.

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