Example 1: Xiaoming has to leave home 1000 meter school before 7: 50 every morning. Xiao Ming started at a speed of 80m/min. Five minutes later, Xiaoming's father found that he had forgotten to bring his Chinese book. So, dad immediately chased Xiao Ming at the speed of 180 m/min and caught up with him on the way.

(1) How long did it take Dad to catch up with Xiaoming?

(2) How far is it from school when catching up with Xiao Ming?

Analysis: Dad catches up with Xiaoming, and they walk the same distance. When solving this problem, we should grasp this reciprocal relationship. (Instruct students to draw circuit diagrams)

Equal relationship:

Dad walks = Xiaoming walks for 5 minutes? +? Xiao Ming walks for x minutes =? The total distance that Xiaoming walked.

The time dad spent? =? How much time did Xiao Ming spend? –? 5 minutes