project with 200 people can complete the task in 15 days. If 50 people are added, how many days can the task be completed in advance?
一项工程200人15天可以完成任务，如果增加50人，可以提前几天完成任务？
<gadget id="calculator">200 * 1 * 15</gadget>
<output>3_000</output>

<gadget id="calculator">200 + 50</gadget>
<output>250</output>

<gadget id="calculator">3_000 / 1 / 250</gadget>
<output>12</output>

<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<result>3</result>