The Nanchuan train departs every 15 minutes, and the Qijiang train departs every 10 minutes. After the trains of the two lines depart at the same time, how many minutes must pass before they depart at the same time.
南川车15分钟发一班，綦江车10分钟发一班，两条线路的车同时发车后，最少经过多少分钟又同时发车．
<gadget id="calculator">2 * 3 * 5</gadget>
<output>30</output>

<result>30</result>