At 9 o'clock, what is the angle formed by the hour and minute hands on the clock face?
9时，钟面上时针和分针组成多少度角．
<gadget id="calculator">360 / 60</gadget>
<output>6</output>

<gadget id="calculator">6 * 15</gadget>
<output>90</output>

<result>90</result>