Question

A train covers a distance of 300 km at a certain average speed.it is speed were decrease by 10 km/hr the journey would take 1 hour longer what is the average speed of the train

Answer 1

hey

) distance covered = 300 km

let the speed of the train = x km/hr

time (t1) = distance/ speed

t1 = 300/ x------(1)

2) distance = 300 km

speed = (x- 10) km

t2 = 300 / (x-10)----(2)

given t2-t1 = 1 hr

300/(x-10)  -  300/x = 1

[300x - 300(x-10)]/ (x-10)x =1

300x -300x +3000 = (x-10)x

3000 = (x-10) x

let x= 60

3000 = (60-10) *60 [true]

therefore 
speed of the train = x = 60km/hr
Hope it helps to you.