SOLUTION: A driver averaged 54 miles per hour on the round trip between home and a city 81 miles away. The average speeds for going and returning were x and y miles per hour Find an express

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Question 637106: A driver averaged 54 miles per hour on the round trip between home and a city 81 miles away. The average speeds for going and returning were x and y miles per hour
Find an expression for y in terms of x

Answer by solver91311(24713) About Me  (Show Source):
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If it is 81 miles from home to city, then it is 162 miles round trip (unless someone picked up home and moved it during the trip). If the average speed for the round trip was 54 mph, then dividing the distance by the rate gives the time of 3 hours for the round trip. Let be the time for the outbound trip at mph, then the time for the return trip had to be at mph.

Given a constant distance, the outbound trip is then and the return trip is . Since 81 equals 81, we can say:



or



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