How do you do the train switcheroo problem?

Question

This math problem is suppose to be solved logically. I'm trying to help my daughter figure it out and I'm having difficulties. Can anyone help?

Answer 1

I'm not sure if there are multiple versions of this problem, but I found a solution on the net:

http://www.puzzles.com/PuzzlePlayground/SwitchTheCars/SwitchTheCarsSol.htm

Let me know if that's the right one or not.