SOLUTION: mary is 12 years old. mary is twice as old as helen was three years ago. how old is helen?

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Question 704330: mary is 12 years old. mary is twice as old as helen was three years ago. how old is helen?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+12+ = Mary's age now
Let +h+ = Helen's age now
+h+-+3+ = Helen's age 3 yrs ago
given:
+12+=+2%2A%28+h+-+3+%29+
+12+=+2h+-+6+
+2h+=+12+%2B+6+
+2h+=+18+
+h+=+9+
Helen is 9
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check:
3 yrs ago Helen was 6
Mary is 12. That is twice 6