SOLUTION: Dorothy is 9 years older than her brother William. If their product of their ages is 360,how old is Dorothy.

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Question 1029441: Dorothy is 9 years older than her brother William. If their product of their ages is 360,how old is Dorothy.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = Dorothy's age
Let +w+ = William's age
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(1) +d+=+w+%2B+9+
(2) +d%2Aw+=+360+
Substitute (1) into (2)
(2) +%28+w%2B9+%29%2Aw+=+360+
(2) +w%5E2+%2B+9w+-+360+=+0+
(2) +%28+w+-+15+%29%2A%28+w+%2B+24+%29+=+0+ ( by looking at it )
(2) +w+=+15+ ( can't use the negative root )
and
(1) +d+=+w+%2B+9+
(1) +d+=+15+%2B+9+
(1) +d+=+24+
Dorothy is 24
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check:
(2) +d%2Aw+=+360+
(2) +24%2A15+=+360+
(2) +360+=+360+
OK