SOLUTION: 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 h

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

RELATED QUESTIONS
Rafael drove to the mountains last weekend. There was heavy traffic on the way there, and (answered by richwmiller)

Keisha drove to the mountains last weekend. There was heavy traffic on the way there, and (answered by mananth,MathTherapy)

Martina drove to the mountains last weekend. There was heavy traffic on the way there,... (answered by mananth)

Chau drove to the mountains last weekend. There was heavy traffic on the way there, and... (answered by ankor@dixie-net.com)

Elsa drove to the mountains last weekend. There was heavy traffic on the way there, and... (answered by lwsshak3,josmiceli)

Frank drove to the mountains last weekend. There was heavy traffic on the way there, and... (answered by ankor@dixie-net.com)

Ryan drove to the mountains last weekend. There was heavy traffic on the way there, and... (answered by ankor@dixie-net.com)

Amy drove to the mountains last weekend. There was heavy traffic on the way there, and... (answered by Alan3354,Edwin McCravy)

Bob drove to the mountains last weekend. There was heavy traffic on the way there, and... (answered by lwsshak3)