How many degrees does the minute hand turn from 8:20 am to 8:50 am?
从早上8：20到8：50，分针转过多少度．
<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<gadget id="calculator">30 * 6</gadget>
<output>180</output>

<result>180</result>