It takes the same time for the master to process 40 parts as for the apprentice to process 30 parts. If the master and apprentice cooperate to process 2100 parts, how many parts will the apprentice process when the task is completed?
师傅加工40个零件和徒弟加工30个零件所用的时间一样，如果师徒合作加工2100个零件，完成任务时徒弟加工的零件有多少个．
<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">2_100 * (3/7)</gadget>
<output>900</output>

<result>900</result>