# A trains travels at a certain speed for a distance of 63km & then travels a distance 72km at an average speed of 6km/h more than its original speed. If it takes 3h to complete the total journey then find its original avg speed

Given distance = 63 km.

Original speed of trian = x cm/hr.

time =distancespeed=63x hrs

And it travels a distance of 72 km at a avg speed of 6 km / hr more than original speed.

distance = 72 km

speed = (x+6) km / m.

time =722+6 hrs.

If it takes 3 hrs to complete the whose journey 63x+72x+6 = 3 hrs

63(x+6)+72x = 3x(x+6)

21(x+6)+24x = x(x+6).

45x+21×6=x2+6x

x2−39x−126=0

(x-42) (x+3) = 0

∴ x = 42 [original avg speed]