A circular tram line, the starting station (also the terminal station) sends a pair of trams in opposite directions at the same time every once in a while, Xiaohua and Xiaoming start from the same place on the line at the same time, walk back along the tram line at the same speed, every Every 10 minutes, they can meet an oncoming tram, and every 15 minutes, another tram catches up with them from behind. It is known that the tram will take 24 minutes to complete the journey. Xiao Ming and Xiao Hua met a few minutes after departure ?
一环形电车路线，起点站(也是终点站)每隔一段时间同时向相反方向发出一对电车，小华和小明同时从线路上同一地点出发，以同样的速度沿着电车线路背向行走，每隔10分钟，他们可以遇到迎面开来的一辆电车，每隔15分钟又都有一辆电车从身后追上他们，已知电车行完全程要24分钟，小明与小华出发后几分钟相遇？
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