Master Wang produces 640 parts in 16 hours, and Master Li produces 516 parts in 12 hours. How many fewer parts does Master Wang produce per hour than Master Li?
王师傅16小时生产640个零件，李师傅12小时生产516个零件．王师傅平均每小时比李师傅少生产零件多少个？
<gadget id="calculator">516 / 12</gadget>
<output>43</output>

<gadget id="calculator">640 / 16</gadget>
<output>40</output>

<gadget id="calculator">43 - 40</gadget>
<output>3</output>

<result>3</result>