At 15:30, what is the angle between the hour and minute hands on the clock face?
15：30时，钟面上的时针和分针的夹角是多少度．
<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<gadget id="calculator">15 + 60</gadget>
<output>75</output>

<result>75</result>