SOLUTION: Returning home form a backpacking weekend, akiko and larry drove at first for 4 hours on a winding mountain road. Once they hit they free way, they were able to increase their spee

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Question 716008: Returning home form a backpacking weekend, akiko and larry drove at first for 4 hours on a winding mountain road. Once they hit they free way, they were able to increase their speed by 35 miles per hour, and they drove for 7 hours until they got home. If the entire trip was 597, miles how fast did they drive on the freeway?
Answer by josgarithmetic(39615) About Me  (Show Source):
You can put this solution on YOUR website!
r = rate driven on the freeway
r-35 = rate on winding road

The distance parts:
Winding Road, %28r-35%29%2A4
Freeway, r%2A7
Whole Trip Home, highlight%28%28r-35%29%2A4%2Br%2A7=597%29, Find r.

Some arithmetic steps:
4r-4%2A35%2B7r=597
11r=597%2B4%2A35
11r=737
ANSWER RESULT, r=67 miles per hour on the freeway.