Question

The distance between delhi and agra is 200 km a train travels the 1st 100km at a speed of 50km/hr.how fast must the train travel the next 100 km,so as to average 70 km/hr for the whole journey

Answer 1

50km per hr + X km per hr = 70 km per hr
so,
70 - 50=X
so, X = 20