SOLUTION: Akiko and Larry drove at first for 4 hours on a winding mountain road. Once they hit the freeway,they were able to increase their speed by 40 miles per hour and drove another 7 hou

Algebra ->  Problems-with-consecutive-odd-even-integers -> SOLUTION: Akiko and Larry drove at first for 4 hours on a winding mountain road. Once they hit the freeway,they were able to increase their speed by 40 miles per hour and drove another 7 hou      Log On


   

Question 1040936: Akiko and Larry drove at first for 4 hours on a winding mountain road. Once they hit the freeway,they were able to increase their speed by 40 miles per hour and drove another 7 hours until they got home. If the trip was 654 miles, how fast did they drive on the freeway?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39614) About Me  (Show Source):
You can put this solution on YOUR website!
Travel rates rule relating rate, time, distance is RT=D.
                    RATE           TIME         DISTANCE
WINDING              r              4            %28r%29%284%29
FREEWAY             r+40            7           %28r%2B40%29%2A%287%29
TOTAL                                             654

Answer by MathTherapy(10549) About Me  (Show Source):
You can put this solution on YOUR website!

Akiko and Larry drove at first for 4 hours on a winding mountain road. Once they hit the freeway,they were able to increase their speed by 40 miles per hour and drove another 7 hours until they got home. If the trip was 654 miles, how fast did they drive on the freeway?
Let speed on the freeway be S

Then speed on winding road = S - 40

We then get the following DISTANCE equation: 7S + 4(S - 40) = 654

Solve for S to get the speed on the freeway