The master and the apprentice made a batch of parts together, the apprentice made (2/5) of the total number, 20 less than the master, how many parts are there in this batch?
师徒二人共做一批零件，徒弟做了总数的(2/5)，比师傅少做20个，这批零件有多少个？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 / (1/5)</gadget>
<output>100</output>

<result>100</result>