How many degrees does the hour hand rotate from 6:00 to 9:00
从6：00到9：00，时针旋转了多少°
<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">360 / 12</gadget>
<output>30</output>

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

<result>90</result>