Math
posted by Lor .
Train A and Train B are traveling towards each other but are 2,100 miles apart. Train A is traveling at 50 mph and Train B is traveling at 35 mph. When will they collide?

The relative velocity is 85mph, and the distance is 2100 miles
In reality, the trains will have to stop for fuel and maintenance.
distance=rate*time
solve for time. 
24.7 hours