Question

peter can drive 25mph faster on the highway than he can on country roads. in the same time it would take peter to drive 70 mi on the country roads. he could, drive 120 mi on the highway . how fast can he drive on each type of road?

Answer 1

Let

x--------> Peter's drive speed on the highway in mph

y--------> Peter's drive speed on country roads in mph

we know that

x=25+y-------> equation 1

70/y=120/x------> 70*x=120*y-----> x=120*y/70------> equation 2

remember that

time=distance/speed

equate equation 1 and equation 2

25+y=120*y/70-----> multiply by 70 both sides

70*[25+y]=120*y-----> 1,750+70*y=120*y-----> 50*y=1,750------> y=35 mph

x=25+35------> x=60 mph

the answer is

Peter's drive speed on the highway is 60 mph

Peter's drive speed on country roads is 35 mph