1. Trams travel from A to B 15 minutes. Every five minutes, you will find that every time a car leaves from A, a tram will arrive at B. Therefore, the topic says that when Liu Li leaves from B, the A car just arrives at B. That is to say, when Liu Li leaves, the A car just leaves from A.

Therefore, the tram 10 from B to A that Liu Li saw was when Liu Li started from B and when Liu Li arrived at A, the train 1 1 was about to start.

Five minutes to send a car is 10 five minutes.

So it takes Liu Li 50 minutes to get from B to A.