There are two people walking at the same time, one is fast and the other is slow. When the slow one is ahead, the fast one can catch up with him after a while. This leads to the "catch-up problem". In essence, it is necessary to calculate the distance that the fast person walks more than the slow person in a certain period of time, that is, to calculate the difference between the distances that two people walk. If a walks fast and b walks slowly,

Walk from a-walk from b.

= A's speed x time -B's speed x time

= (speed of a-speed of b) × time.

Usually, the speed difference should be considered when chasing questions.

Example: At 8: 08 in the morning, Xiaoming set off from home by bike. Eight minutes later, his father came after him on a motorcycle and caught up with him 4 kilometers away from home. Then his father went home immediately. When he got home, he went back to chase Xiao Ming. When he caught up with Xiao Ming, he was just 8 kilometers away from home. What time is it?

Solution: Draw a simple schematic diagram:

As can be seen from the picture, Xiao Ming left from the first time his father chased him to the second time.

8-4 = 4 (km).

The distance that Dad rides is 4+8 = 12 (km).

This shows that the speed of dad riding a motorcycle is 12 ÷ 4 = 3 (times) that of Xiaoming riding a bike. According to this multiple, Xiaoming rides 8 kilometers, and Dad can ride 8× 3 = 24 (kilometers).

But in fact, my father's riding time is 8 minutes less.

4+ 12 = 16 (km).

Ride 24- 16 = 8 (km) less.

Motorcycle speed 1 km/min, dad riding 16 km takes 16 minutes.

8+8+ 16=32.

A: It was 8: 32.

Is it okay?