Question

a man drives his car on a highway the speed limit is 60 kilometre per hour he covers a distance 240 km at a uniform speed on road if he increases speed by 20km/hr he can reach his destination 1 hour earlier. what is original speed at which he travels atchually??

Answer 1

Let the actual speed of the car be x

Actual Time taken by the car = 240/x

If he increases the speed by 20km/hr 

speed = x + 20

Time taken = 240/ x+ 20

According to the question

240/x - 240/ x+ 20 = 1

240 [ 1 /x - 1/ x+ 20] = 1

240 [ x + 20 - x/x2 +20x ] = 1

240 * 20 = x2 +20x

 x2 +20x - 4800 = 0

 x2 +80x - 60x - 4800 = 0 

x (x + 80) -60 (x+ 80) = 0

(x -60)  (x + 80) =0

x = 60  or x = -80

But speed cant be negative

Thus    x = 60 km/hr
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Answer 2

Answer:

here is your answer..............