Master Gao made 336 parts in 16 hours, and Master Wang made 392 parts in 14 hours. How many parts per hour does Master Gao make less than Master Wang?
高师傅16小时做了336个零件，王师傅14小时做了392个零件．高师傅比王师傅平均每小时少做多少个零件？
<gadget id="calculator">392 / 14</gadget>
<output>28</output>

<gadget id="calculator">336 / 16</gadget>
<output>21</output>

<gadget id="calculator">28 - 21</gadget>
<output>7</output>

<result>7</result>