Master Wang processes a batch of parts, 20 per day, which can be completed 1 day in advance. After working for 4 days, due to the improved technology, 5 more pieces can be processed every day, and the result is completed 3 days ahead of schedule. Q: How many parts are there in this batch?
王师傅加工一批零件，每天加工20个，可以提前1天完成．工作4天后，由于改进了技术，每天可以多加工5个，结果提前3天完成．问：这批零件有多少个？
<gadget id="calculator">25 - 1</gadget>
<output>24</output>

<gadget id="calculator">24 * 20</gadget>
<output>480</output>

<result>480</result>