SOLUTION: Two cars (a race car and a normal car) each travel 300 miles per day. The race car travels 40 mph faster and takes 2 hours and 40 minutes less time than the normal car. Find the sp
Algebra ->
Customizable Word Problem Solvers
-> Travel
-> SOLUTION: Two cars (a race car and a normal car) each travel 300 miles per day. The race car travels 40 mph faster and takes 2 hours and 40 minutes less time than the normal car. Find the sp
Log On
Question 716032: Two cars (a race car and a normal car) each travel 300 miles per day. The race car travels 40 mph faster and takes 2 hours and 40 minutes less time than the normal car. Find the speed of the race car. Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website! Two cars (a race car and a normal car) each travel 300 miles per day. The race car travels 40 mph faster and takes 2 hours and 40 minutes less time than the normal car. Find the speed of the race car.
**
let x=speed of the race car
x-40=speed of the normal car
2 hours and 40 minutes=2-2/3 hours=8/3 hrs
..
travel time=distance/speed
travel time of normal car-travel time of race car=2-2/3 hrs
300/(x-40)-300/x=8/3
900/(x-40)-900/x=8
900x-900(x-40)=8x(x-40)
900x-900x+36000=8x^2-320x
8x^2-320x-36000=0
x^2-40x-4500=0
(x+50)(x-90)=0
x=-50 (reject)
or
x=90
x-40=50
speed of the race car=90 mph
speed of the normal car=50 mph
(