A worker processes a batch of machine parts, completes (1/5) of the task on the first day, completes the rest (1/3) on the second day, and completes 20 more parts on the second day than on the first day. How many parts are there in total?
一工人加工一批机器零件，第一天完成任务的(1/5)，第二天完成了剩下部分的(1/3)，第二天比第一天多完成20个．这批零件共有多少个．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(4/5) * (1/3)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">(4/15) - (1/5)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">20 / (1/15)</gadget>
<output>300</output>

<result>300</result>