SOLUTION: Karen traveled 640 miles by boat and returned by plane. She spent 42 hours traveling on the trip. If the plane is 20 times faster than the rate of the boat, find each rate.

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Question 635016: Karen traveled 640 miles by boat and returned by plane. She spent 42 hours traveling on the trip. If the plane is 20 times faster than the rate of the boat, find each rate.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = time spent traveling by boat
+42+-+t+ = time spent traveling by plane
Let +r+ = rate by boat
Let +20r+ = rate by plane
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Equation for boat:
(1) +640+=+r%2At+
(2) +640+=+20r%2A%28+42+-+t+%29+
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(2) +640+=+840r+-+r%2At+
Substitute (1) into (2)
(2) +640+=+840r+-+640+
(2) +1280+=+840r+
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You can finish. Find +r+
and +20r+