Since the first train has been travelling for 3 hours, we have the following equations:
We want to know when they will be equal, so set these equal to eachother:
So 15 hours after the second train leaves, they will be at the same distance. This is at 8AM since the second train leaves at 5PM.
We want to know when they will be equal, so set these equal to eachother:
So 15 hours after the second train leaves, they will be at the same distance. This is at 8AM since the second train leaves at 5PM.