long-distance bus station sends a car to the east line every 20 minutes, and sends a car to the west line every 15 minutes. Now it sends a car to both lines at the same time. How many minutes have passed before it leaves at the same time?
某长途汽车站向东线每20分钟发一辆车，向西线，每15分钟发一辆车，现在同时向两线发车，至少经过多少分钟又同时发车？
<gadget id="calculator">2 * 2 * 3 * 5</gadget>
<output>60</output>

<result>60</result>