There is a tram running from Station A to Station B. It departs every 5 minutes. The whole journey takes 15 minutes. Xiao Zhang rides a bicycle from Station B to Station A along the tram line. When he leaves, there happens to be a tram arriving at Station B. On the way, he encounters a There are 8 oncoming trams. When they arrive, there happens to be a tram departing from Station A. How many minutes does it take for him to travel from Station B to Station A?
有一路电车从甲站开往乙站，每5分钟发车一趟，全程共需15分钟，小张从乙站骑自行车沿电车线去甲站，出发时恰好有一辆电车到达乙站，在路上又遇到8辆迎面开来的电车，到达时恰好有一辆电车从甲站出发，他从乙站到甲站共用多少分钟．
<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<gadget id="calculator">6 * 5</gadget>
<output>30</output>

<result>30</result>