Faster train = x+8
Slower train = x
The trains approach each other at their combined speed x + x+8
and at this speed they cover the 432 miles in 4 hours (from 10 AM to 2 PM)
Rate * Time = distance
(x+ x+8) * 4 = 432
4x+4x+32 = 432
8x = 400
x = 50 mph = slower train
x+8 = 58 mph = faster train