SOLUTION: Donna drove half the distance of a trip at 40 mi/h. At what speed would she have to drive for the rest of the distance so that the average speed for the entire trip would be 45 mi/

Question 397647: Donna drove half the distance of a trip at 40 mi/h. At what speed would she have to drive for the rest of the distance so that the average speed for the entire trip would be 45 mi/h?
Answer by robertb(5830) (Show Source): You can put this solution on YOUR website!
Let d = total distance
x = speed in the 2nd half of trip
==> length of time in 1st half of trip =
length of time in 2nd half of trip =
Then

==> mi/hr.
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