Question 1169435
distance=v*t
v=freight and it takes t hours so the speed is 600/t
for the express it takes 600/(t-2) hours
600/(t-2)-50=600/t
multiply by t(t-2)
600t-50t^2+100t=600t-1200
0=50t^2-100t-1200
0=t^2-2t-24=(t-6)(t+4)
only positive root is t=6 hours
so the the velocity for the express train is 100 kph and the express is 150 kph and takes 4 hours, 2 hours fewer, to go the same distance.