Question 921857: Jim drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took 12 hours. When Jim drove home, there was no traffic and the trip only took 8 hours. If his average rate was 20 miles per hour faster on the trip home, how far away does Jim live from the mountains?
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! Jim drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took 12 hours.
When Jim drove home, there was no traffic and the trip only took 8 hours.
If his average rate was 20 miles per hour faster on the trip home, how far away does Jim live from the mountains?
:
let s = his speed in traffic
then
(s+20) = his speed coming home
:
Write a distance equation; dist = time * speed
the dist there and back was the same, therefore
12s = 8(s+20)
12s = 8s + 160
12s - 8s = 160
4s = 160
s = 160/4
s = 40 mph in traffic
"how far away does Jim live from the mountains?"
12 * 40 = 480 mi
Check it by finding the distance when he drove 20 mph faster
8 * 60 = 480 mi
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