SOLUTION: The distance between two cities is ninety miles, and a woman drives from one city to the other at a rate of forty-five mph. At what rate must she return if the total travel time is

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Question 121672: The distance between two cities is ninety miles, and a woman drives from one city to the other at a rate of forty-five mph. At what rate must she return if the total travel time is three hours and forty minutes?
Found 2 solutions by checkley71, edjones:
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
90/45=2 HOURS FOR THE GOING TRIP.
90/X=(3 2/3-2)
90/X=(1 1/3)
(1 1/3)X=90
X=90/(1 1/3)
X=67.5 MPH FOR THE RETURN TRIP.
PROOF:
2*45+(1 1/3)*67.5=180
90+90=180
180=180

Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
rt=d
45t=90
45t/45=90/45
t=2 hrs going.
.
3h 40m-2h=1h 40m=1 2/3h=5/3h time of return trip.
5r/3=90
5r/3 * 3/5=90* 3/5
r=54 mph rate of return.