The master and apprentice process a batch of parts, and the ratio of their work efficiency is 5:3. When the task is completed, the apprentice processed 240 pieces, how many pieces did the master ask the master to make? (column proportional equation solution)
师徒两人加工一批零件，他们工作效率之比是5：3．任务完成时徒弟加工240个，求师傅做了多少个？(列比例方程解)
<gadget id="calculator">5 / 3</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">(5/3) * 240</gadget>
<output>400</output>

<result>400</result>