The two masters and apprentices processed a batch of parts. It was originally planned that the master would process 62.5% of the total number of parts, and the apprentices would complete the rest. The actual master processed 1200 parts, more than 20% of the assigned tasks. Do you know how many parts the apprentice actually needs to process?
师徒二人加工一批零件，原计划师傅加工总零件个数的62.5%，剩下的由徒弟完成．实际师傅加工了1200个零件，超过分配任务的20%．你知道徒弟实际只需加工多少个零件吗？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1_200 / (6/5)</gadget>
<output>1_000</output>

<gadget id="calculator">62.5 / 100</gadget>
<output>0.625</output>

<gadget id="calculator">1_000 / 0.625</gadget>
<output>1_600</output>

<gadget id="calculator">1_600 - 1_200</gadget>
<output>400</output>

<result>400</result>