Question

A train is traveling at a speed of 60 km/h from Delhi to Kolkata. On its return Journey, it travels at
a speed of 50km/h and takes 4hrs more than the onward journey. What is the distance between
Delhi and Kolkata?​

Answer 1

60 km/hr = x hrs

50 km/hr = x + 4 hrs

60x = 50( x + 4 )

60x = 50x + 200

10x = 200

x = 20

distance = 60x = 50( x + 4 ) = 60 × 20

       = 1200 km

Answer 2

Answer:

Let t be the time of onward journey

We know that, Distance = Speed * Time

For the onward journey, i.e, Delhi to Kolkata

Distance = ( 60 * t ) km

On the return journey, i.e, Kolkata to Delhi

Time = (t + 4) hour

Therefore, Distance = 50 * ( t + 4 )

From ( 1 ) and ( 2 ), we have

60t = 50( t + 4 )

60t = 50t + 200

60t - 50t = 200

10t  = 200

t = 200/10

t = 20 hours

Therefore, Distanace between Delhi and Kolkata = 60 * t

                                                                                  = 60 * 20

                                                                                  = 1200 km