From 8:00 to 12:00 on a certain day, Master Wang processed 120 parts in total. How many parts does he process per hour on average?
某日的8时到12时，王师傅共加工120个零件，他平均每小时加工多少个零件．
<gadget id="calculator">120 / 4</gadget>
<output>30</output>

<result>30</result>