Solution: Let A's distance per minute be X and B's distance per minute be 0.8x Suppose A passes B's car m minutes after its departure, then there will be (M- 1 1) minutes for A and (M-7) minutes for B. Column equation:

0.8x*(M-7)=x*(M- 1 1)

0.8*(M-7)=M- 1 1)

0.2M=5.4

M=27

A: Twenty-seven minutes after B leaves, A will overtake B. ..

According to the analysis of the questions, B actually took 8 minutes longer than A. From the speed relationship of 80%, we assume that A's speed is 5, B's speed is 4, and the total length of X is X, then X/4-X/5 = 8, X = 160, which means that the total length is 160. Midpoint 80, b starts at 44, and then every minute.