Question

An express train maker ad
in makes a run of 240 km at a certain speed.
Another train whose sbeed is 12 km/hut less Bn takes
how longer to make the same trip. Find the speed of the
express train.​

Answer 1

Answer:

60km/h

Step-by-step explanation:

total distance = 240 km

let speed = x km/hr

therefore time = 240/x hrs

new speed = x-12 km/hr

therefore time = 240/x-12 hrs

given difference = 1 hr

therefore 240/x-12 - 240/x=1

240x-240x+2880/x2-12x =1

2880 = x2-12x

x2-12x-2880=0

by completing the squares

x=60 or x = -48

speed is non negative 

therefore original speed of train = 60 km/hr