Master Wang produces 648 parts in 8 hours, and Master Li produces 72 parts in 4 hours. How many more parts does Master Wang produce per hour than Master Li?
王师傅8小时生产648个零件，李师傅4小时生产72个零件．王师傅平均每小时比李师傅多生产零件多少个？
<gadget id="calculator">648 / 8</gadget>
<output>81</output>

<gadget id="calculator">72 / 4</gadget>
<output>18</output>

<gadget id="calculator">81 - 18</gadget>
<output>63</output>

<result>63</result>