Solution: If the starting speed of Party A is V A, the speed of Party B is V B, the speed of Party A after acceleration is V A, and the time taken is X minutes, then the formula can be: 3VA-3VB =15VB-15VA, 5V A-5V B =xV B-XV A. The most important thing in the formula is to find the equivalence relation. This problem is a pursuit problem, and it must be understood that all running is a circle. The problem-solving skill is to put forward the same factor after the formula and divide the last two formulas up and down. The answer is 25 minutes.