The bus terminal sends out two buses at the same time. The two buses leave one every 9 minutes and 12 minutes respectively. How many minutes have passed since the first departure at the same time before the two buses leave at the same time?
公交总站同时发出两路公交车，这两路公交车分别是每9分钟和12分钟各发一辆，第一次同时发车后经过多少分钟，两路公交车又同时发车？
<gadget id="calculator">2 * 2 * 3 * 3</gadget>
<output>36</output>

<result>36</result>