SOLUTION: At what speed must a biker return from Town B to Town A, a distance of 30 miles, if the trip there took 2 hours and 30 minutes, and he wishes to average 15 miles per hour for the e

Question 474189: At what speed must a biker return from Town B to Town A, a distance of 30 miles, if the trip there took 2 hours and 30 minutes, and he wishes to average 15 miles per hour for the entire trip?
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!

 

Hi,

Note:  D = r*t  OR r = D/t

 r = 30mi/2.5hr = 12mph , the rate to 

  Let x represent rate back...

wishing to average 15mph for the entire trip

    (12mph + x)/2) = 15mph

              x = 18mph 

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