SOLUTION: Pete is twice as old as Mary. 7 years ago the sum of their ages was 31. Find their ages

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Question 1147791: Pete is twice as old as Mary. 7 years ago the sum of their ages was 31. Find their ages


Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = Mary's age now
+2x+ = Pete's age now
-------------------------------------
+%28+x+-+7+%29+%2B+%28+2x+-+7+%29+=+31+
+x+-+7+%2B+2x+-+7+=+31+
+3x+=+31+%2B+14+
+3x+=+45+
+x+=+15+
and
+2x+=+30+
------------------
Mary is 15
Pete is 30
-----------------
Check:
7 yrs ago the sum of their ages was:
+15+%2B+30+-+7+-+7+=+31+
OK