To build a 2,400-meter-long road, it was originally planned that 30 people would repair it, and each person would repair 10 meters a day, and the task was completed on time. 10 people were added to the actual road repair. If the daily workload of each person remains the same, how many days can the repair be completed in advance?
要修一条长2400米的公路，原计划30人修，每人每天修10米，正好按时完成任务．实际修路时增加了10人，如果每人每天的工作量不变，那么可提前几天修完？
<gadget id="calculator">30 * 10</gadget>
<output>300</output>

<gadget id="calculator">2_400 / 300</gadget>
<output>8</output>

<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<gadget id="calculator">40 * 10</gadget>
<output>400</output>

<gadget id="calculator">2_400 / 400</gadget>
<output>6</output>

<gadget id="calculator">8 - 6</gadget>
<output>2</output>

<result>2</result>