Let's calculate the time required for the clock to start again, and go back to Uncle Li:

9:00 is the evening time, actually it is 2 1:00.

(This problem needs to be converted into 24-hour timing. )

21:00-12:10 = 8 hours and 50 minutes

Then calculate the working hours of Uncle Li when he goes to work in the factory:

3 pm = 15 pm 1 1 point =23 pm.

23:00- 15:00=8 hours

50 minutes includes round-trip time and 10 minutes in advance.

So the one-way time: (50- 10)/2=20 minutes.

Which means he left at 2: 30 pm,

14: 30-12:10 = 2 hours and 20 minutes = 140 minutes.