road construction team plans to build a 12,000-meter-long road. It plans to repair 300 meters per day and implements 400 meters per day. So how many days earlier than the original plan was it actually completed?
一个修路队准备修一条长12000米的公路，每天计划修300米，实行每天修400米．这样实际比原计划提前几天修完？
<gadget id="calculator">12_000 / 300</gadget>
<output>40</output>

<gadget id="calculator">12_000 / 400</gadget>
<output>30</output>

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

<result>10</result>