SOLUTION: zelma is eighteen years older than her son. she was three times as old as he was oneyear ago. how old are they now?

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Question 691607: zelma is eighteen years older than her son. she was three times as old as he was oneyear ago. how old are they now?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = her age now
Let +b+ = her Son's age now
+a-1+ = her age 1 year ago
+b-1+ = her Son's age 1 year ago
given:
(1) +a+=+b+%2B+18+
(2) +a+-+1+=+3%2A%28+b+-+1+%29+
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Substitute (1) into (2)
(2) +b+%2B+18+-+1+=+3%2A%28+b+-+1+%29+
(2) +b+%2B+17+=+3b+-+3+
(2) +2b+=+20+
(2) +b+=+10+
and, since
(1) +a+=+b+%2B+18+
(1) +a+=+10+%2B+18+
(1) +a+=+28+
Zelma is 28
Her Son is 10
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check:
(2) +a+-+1+=+3%2A%28+b+-+1+%29+
(2) +28+-+1+=+3%2A%28+10+-+1+%29+
(2) +27+=+3%2A9+
(2) +27+=+27+
OK