Speed of the trains

Question

Train B travels 25 mph faster than train A. Train A travels 300 miles in the same time it takes Train B to travel 400 miles.Find the speed of both trains.

Answer 1

400/300 = (x+25)/x = 1 + 25/x = 4/3

3x + 75= 4x

x = 75 mph = train A's speed

x+25 = 100 mph = train B's speed

B did 400 miles in 4 hours at 100 mph 4x100 = 400

A did 300 miles in 4 hours at 75 mph 4x75=300