Question 1049036
Let r represent your speed in mph. 25/60=5/12 hour. So:
480/r=480/(r+5)+5/12 hr
5760/r=5760/(r+5)+5
5760(r+5)=5760r+5(rē+5r)
5760r+28800=5760r+25r+5rē
5rē+25r-28800=0
rē+5r-5760=0
Using the quadratic formula; we get r=73.436, and -78.436. Throwing out the negative result, we get the average speed going there as 73.436 mph; going back the average speed was 78.436.
Total drive time there:480/73.436=6.54 hours
Total drive time back:480/78.436=6.12 hours