Question

A CAR DOES A JOURNEY WITHOUT STOPPING FOR 7 HOURS. IF IT HAD TRAVELLED 10 KM/H FASTER IT WOULD HAVE COMPLETE JOURNEY IN 5 H 20 MIN. WHAT IS SLOWER SPEED

Answer 1

let the speed of the car be = x
let the distance travelled be = y

We know that time = d/s

so 7=y/x
 7x=y                                         .............................. 1

If we increase the speed by 10 KM/H so = x+10

time is taken if the speed is (x+10)  5 h 20 min i.e   5+1/3=16/3
So,
time = d/s

16/3=y/(x+10)

 16x-3y= -160 ......................... 2

Now substitute the value of  1 in 2.

 16x-3(7x)= -160
 
 16x-21x = -160

       -5x = -160

          x=32

Substitute the value of x in eq 1

 7(32)=y
 
      y=224.
Hence, the speed is 32kmph.