Question 992175: greg drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took 8 hours. When Greg drive home, there was no traffic and the trip only took 5 hours. If his average rate was 21 mph faster on the trip home, how far away does Greg live from the mountains?
Answer by Edwin McCravy(20081)   (Show Source):
You can put this solution on YOUR website! Greg drove to the mountains last weekend. There was heavy
traffic on the way there, and the trip took 8 hours. When
Greg drive home, there was no traffic and the trip only
took 5 hours. If his average rate was 21 mph faster on
the trip home, how far away does Greg live from the
mountains?
Let the answer be that Greg lives x miles from the mountains.
>>...on the way there,...the trip took 8 hours...<<
So his average rate going to the mountains was x miles per
8 hours or x/8 mph.
>>... When Greg drive home,...the trip...took 5 hours...<<
So his average rate coming home from the mountains was x
miles per 5 hours or x/5 mph
>>...his average rate was 21 mph faster on the trip home...<<
So the equation is
x/5 = x/8 + 21
Solve that by multiplying through by LCD = 40
The answer is somewhere between 250 and 300 miles.
Edwin
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