Train A and Train B leave the station at the same time. Train A is northbound, and Train B is eastbound travelling 20 miles per hour faster than Train A. After 2 hours, they are 200 miles apart. How fast is Train A travelling?

Solution:

Speed of A: x

Speed of A: x+20

So

200 = 2(x+x+20)

x =40

So speed of A is 40 mph