It takes 8 hours for the master to process a batch of parts, and 12 hours for the apprentice to do it alone. The master and apprentice cooperate. When the task is completed, the apprentice processes 240 parts. How many parts does the apprentice process per hour on average?
加工一批零件，师傅单独做需8小时完成，徒弟单独做需12小时完成，师徒合作，在完成任务时，徒弟加工了240个零件，徒弟平均每小时加工多少个零件？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/8) + (1/12)</gadget>
<output>5/24 = around 0.208333</output>

<gadget id="calculator">1 / (5/24)</gadget>
<output>24/5 = around 4.8</output>

<gadget id="calculator">240 / (24/5)</gadget>
<output>50</output>

<result>50</result>