Master Wang originally planned to make 80 parts per day, but actually made 20 fewer parts per day than the original plan. As a result, the task was delayed for 5 days. How many days did Master Wang actually spend making this batch of parts?
王师傅原计划每天做80个零件，实际每天比原计划少做20个，结果推迟5天才完成任务．王师傅实际用了多少天做这批零件？
<gadget id="calculator">80 * 5</gadget>
<output>400</output>

<gadget id="calculator">20 - 80</gadget>
<output>-60</output>

<gadget id="calculator">80 + (-60)</gadget>
<output>20</output>

<gadget id="calculator">400 / 20</gadget>
<output>20</output>

<result>20</result>