To build a 12,000-meter-long road, the original plan was to build 300 meters per day, but the task was completed in 30 days. How much more meters was actually built per day than the original plan?
修一条长12000米的公路，原计划每天修300米，结果30天完成了任务，实际比原计划每天多修多少米？
<gadget id="calculator">12_000 / 30</gadget>
<output>400</output>

<gadget id="calculator">400 - 300</gadget>
<output>100</output>

<result>100</result>