How many minutes have elapsed if the minute hand on the clock rotates 120°?
在时钟上分针旋转120°，则时间经过了多少分钟．
<gadget id="calculator">360 / 12</gadget>
<output>30</output>

<gadget id="calculator">120 / 30</gadget>
<output>4</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<result>20</result>