15. (15 points) Two cars, A and B, are traveling towards each other on a road parallel to a railway. A 180-meter-long train is moving in the same direction as car A at a speed of 60 kilometers/hour. The train takes 5 minutes from the moment it catches up with car A to the moment it meets car B. If the train takes 30 seconds to pass car A completely and 6 seconds to pass car B completely. How many minutes after car B meets the train will it meet car A?
【Solution】Solution: 60 km/h $=16.67$ m/s, 5 min $=300$ s.
(1) The speed of car A is:
$$
\begin{array}{l}
16.67-180 \div 30, \\
=16.67-6, \\
=10.67 \text { (m/s). }
\end{array}
$$
(2) When the train meets car B, the distance between car A and car B is:
$$
\begin{array}{l}
300 \times(16.67-10.67), \\
=300 \times 6, \\
=1800 \text { (m); }
\end{array}
$$
(3) The speed of car B is:
$$
\begin{array}{l}
180 \div 6-16.67, \\
=30-16.67, \\
=13.33 \text { (m/s); }
\end{array}
$$
(4) The time required for car A and car B to meet is:
$$
\begin{array}{l}
1800 \div(10.67+13.33), \\
=1800 \div 24, \\
=75 \text { (s), } \\
=1.25 \text { (min). }
\end{array}
$$

Answer: After car B meets the train, it will take another 1.25 minutes for car B to meet car A.