From 8:00 to 12:00, Master Wang processed a total of 320 parts, how many parts per hour on average.
从8时到12时，王师傅共加工320个零件，平均每小时加工多少个零件．
<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<gadget id="calculator">320 / 4</gadget>
<output>80</output>

<result>80</result>