SOLUTION: An automobile travels 280 km at a certain speed. If the speed had been 5km/h faster, the trip would've been made in one hours less time. Find the original speed of the automobile.

Question 830844: An automobile travels 280 km at a certain speed. If the speed had been 5km/h faster, the trip would've been made in one hours less time. Find the original speed of the automobile.
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
An automobile travels 280 km at a certain speed. If the speed had been 5km/h faster, the trip would've been made in one hours less time. Find the original speed of the automobile.
..
let x=original speed of auto
x+5=speed of auto resulting in one hour less travel time
travel time=distance/speed
..

280x+1400-280x=x(x+5)
1400=x^2+5x
x^2+5x-1400=0
(x+40)(x-35)=0
x=-40 (reject, x>0)
or
x=35
original speed of the automobile=35 km/hr

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