Answer:
The combined speeds of the trains equals 800 miles per 4 hours or
200 miles per hour.
This averages out to 100 miles per hour for each train.
Westbound train is 18 mph faster so
109 mph = Westbound
91 mph = Eastbound
That seems to be right except trains speeds of 91 mph and 109 mph seem to be VERY fast.
Explanation: