The park is the starting point of the No. 1 and No. 3 cars. The No. 1 car departs every 20 minutes, and the No. 3 car departs every 30 minutes. After the two cars depart at the same time, they will depart at least how many minutes later.
公园是1路车和3路车的起点站，1路车每隔20分钟发车一次，3路车每隔30分钟发车一次，这两辆车同时发车后至少再过多少分钟又同时发车．
<gadget id="calculator">2 * 5 * 2 * 3</gadget>
<output>60</output>

<result>60</result>