factory wants to make a batch of parts. The original plan is to make 250 parts per day, and it will be completed in 30 days. Actually do 50 more than the original plan every day, how many days will it actually take to complete? (answer with ratio)
某工厂要制作一批零件，原计划每天制作250个，30天完成．实际每天比原计划多做50个，实际需要几天完成？(用比例解答)
<gadget id="calculator">250 * 30</gadget>
<output>7_500</output>

<gadget id="calculator">250 + 50</gadget>
<output>300</output>

<gadget id="calculator">7_500 / 300</gadget>
<output>25</output>

<result>25</result>