The master and the apprentice worked together to process a batch of parts. As a result, the apprentice completed 30 parts, accounting for (3/5) of the total number of parts. How many parts did the master complete?
师徒两人合作加工一批零件，结果徒弟完成了30个，占零件总数的(3/5)，师傅完成了多少个零件？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 / (3/5)</gadget>
<output>50</output>

<gadget id="calculator">50 - 30</gadget>
<output>20</output>

<result>20</result>