A bus travelling at 42 km/h completes a journey in 20 hours. At what speed will it haveto cover the same distance in 12 hours?

Correct option is C

​Given:

Speed of the bus for the original journey = 42 km/h

Time for the original journey = 20 hours

Time for the new journey  = 12 hours

Formula Used:

Distance = Speed × Time

Solution: 

Let the distance for the original journey be D

Distance covered in the original journey:

D = 42 ×20 = 840km

Now, the new speed to cover the 840 km in 12 hours:

New Speed = $$\frac{840}{12} = 70 \, \text{km/h}$$​​