Required Mathematical Intelligence

Chapter 24 Aligning Tables
This is what happened in the 50's.Mr. Zhang, an old worker, bought a new big wall clock at his home, and left after winding the clock.But I didn't have a watch at home, nor a radio, so I couldn't adjust the time of the watch, so I had to go to Master Li's house not far away to check the watch.Because the wall clock was too big, it was inconvenient to pick it up. Master Zhang went to Master Li’s house empty-handed and sat for a while, then adjusted the watch when he came back.How did he do it?
[Answer: Master Zhang winds the wall clock at home, check the time before leaving, and set it to t1. Immediately after arriving at Master Li’s house, check the time first, set it to t2, and then check the time when leaving, set it to t3, so that you can know The time spent at Master Li’s house is t3-t2. When you get home, check the time immediately and set it to t4. You can calculate the time on the road as (t4-t1)-(t3-t2)=t.Therefore, the current time can be calculated Time=t/2 t3.]
(End of this chapter)