SOLUTION: Martina drove to the mountains last weekend. There was heavy traffic on the way there, and the trip 8 took hours. When Martina drove home, there was no traffic and the trip only 5

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Martina drove to the mountains last weekend. There was heavy traffic on the way there, and the trip 8 took hours. When Martina drove home, there was no traffic and the trip only 5       Log On

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Question 800726: Martina drove to the mountains last weekend. There was heavy traffic on the way there, and the trip 8 took hours. When Martina drove home, there was no traffic and the trip only 5 took hours. If her average rate was 21 miles per hour faster on the trip home, how far away does Martina live from the mountains?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
let Martina live x miles from the mountains
Let her rate to mountains be y
t=d/r
x/y = 8
x=8y
Return trip 5 hours
rate = y+21
x/(y+21) =5
substitute x
8y/(y+21)=5
8y=5y+105
8y-5y=105
3y=105
y= 105/3
y=35
x=8y
x=8*35= 280 miles
distance to the mountain = 280 miles