How many degrees does the hour hand rotate from 6 o'clock to 9 o'clock?
从6点到9点，时针旋转了多少度．
<gadget id="calculator">360 / 12</gadget>
<output>30</output>

<gadget id="calculator">3 * 30</gadget>
<output>90</output>

<result>90</result>