SOLUTION: Peter can drive 25 mph faster on the highway than he can on country roads. In the time it would take Peter to drive 70 mi on country roads, he could drive 120 mi on the highway. Ho

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Peter can drive 25 mph faster on the highway than he can on country roads. In the time it would take Peter to drive 70 mi on country roads, he could drive 120 mi on the highway. Ho      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 1114056: Peter can drive 25 mph faster on the highway than he can on country roads. In the time it would take Peter to drive 70 mi on country roads, he could drive 120 mi on the highway. How fast can he drive on each type of road?
Found 3 solutions by amalm06, greenestamps, josgarithmetic:
Answer by amalm06(224) About Me  (Show Source):
You can put this solution on YOUR website!
Denote highway speed as Vh and country speed as Vc. Then

Vh=Vc%2B25

70=%28Vh-25%29t

120=Vh%2At

%28120%2F70%29=%28Vh%29%2F%28Vh-25%29

120Vh-3000=70Vh

50Vh=3000

Vh=60,Vc=35 (Answer)

Answer by greenestamps(13216) About Me  (Show Source):
You can put this solution on YOUR website!


The difference in speeds is 25mph; the difference in distances is 2 hours.

So the speed he can go on country roads is 70/2 = 35mph; the speed he can go on the highway is 120/2 = 60mph.

Answer by josgarithmetic(39631) About Me  (Show Source):
You can put this solution on YOUR website!
              SPEEDS       TIME      DISTANCE
COUNTRY        r            t           70
HIGHWAY        r+25         t          120

highlight_green%2870%2Fr=120%2F%28r%2B25%29%29
7%28r%2B25%29=12r
7r%2B175=12r
5r=175
highlight%28r=35%29------country road speed
--
highlight%2860%29-------highway speed