Master Li and Master Zhang worked for 4 hours at the same time, Master Li processed 156 parts, and Master Zhang added 140 parts. How many more parts does Master Li process per hour than Master Zhang?
李师傅和张师傅同时工作了4小时，李师傅加工了156个零件，张师傅加140个零件．李师傅每小时比张师傅多加工了多少个零件？
<gadget id="calculator">156 - 140</gadget>
<output>16</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<result>4</result>