a car cover a distance of 715 km. with some speed.if speed of car is 10km/hour more,then it take 2 hour less to cover that distance.then initially what was the speed of the car?	Pick one:
A) 45km/h  B) 50km/h  C) 55km/h  D) 65km/h  E) none of these
let speed=x km./hour.then,   715/x-715/(x+10)=2,1/x-1/(x+10)=2/715;(x+10)-x/x(x+10)=2/715   2x(x+10)=7150;2x^2+20x-7150=0   x^2+10x-3575=0;x^2+65x-55x-3575=0   x(x+65)-55(x+65)=0;(x+65)(x-55)=0   x=55,because x can't be -65   answer 55km/h
<result>C</result>
a car cover a distance of 715 km. with some speed.if speed of car is 10km/hour more,then it take 2 hour less to cover that distance.then initially what was the speed of the car?