Question 925619
Distances will be the same the faster train catches  the slower one 
t the time for the slower train
75kph(t) = 125kph(t-1)
125 = 50t
2.5hr = t, the time for the slower train
..........
 How far from station M will the faster train catch the slower one?
Distance traveled: 75kph(2.5hr) = 187.5mi