SOLUTION: Three years ago my brother was twice as old as my sister. Now he is 12 years older than she is. How old is my sister now?

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Question 1094940: Three years ago my brother was twice as old as my sister. Now he is 12 years older than she is. How old is my sister now?
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
x, sister
y, brother
system%28y-3=2%28x-3%29%2Cy=x%2B12%29

x%2B12-3=2x-6
highlight%2815=x%29
-
highlight%28y=27%29

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!

If your brother is 12 years older than your sister now, then he was also 12 years older then her three years ago.

If three years ago he was twice as old as her, then, since the difference in their ages is 12, three years ago he was 24 and she was 12.

So today he is 27 and your sister is 15.