The 4,000-meter-long road was originally planned to be repaired by 4 meters per person per day, and 20 people were sent to complete the repair. The actual repair time increased by 5 people, and the task could be completed a few days in advance.
长4000米的公路，原计划每人每天修4米，派20人来完成，实际修时增加了5人，可以提前几天完成任务．
<gadget id="calculator">4 * 20</gadget>
<output>80</output>

<gadget id="calculator">4_000 / 80</gadget>
<output>50</output>

<gadget id="calculator">20 + 5</gadget>
<output>25</output>

<gadget id="calculator">4 * 25</gadget>
<output>100</output>

<gadget id="calculator">4_000 / 100</gadget>
<output>40</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<result>10</result>