The road construction team paved a road, starting to pave 400 meters a day, and paved half of the road in 12 days. In the future, we will pave 200 meters more every day, which happens to be completed within the planned date. How many days were originally planned?
筑路队铺一条路，开始每天铺400米，12天铺了这条路的一半．以后每天多铺200米，恰好在计划日期内完成，原计划用多少天？
<gadget id="calculator">400 + 200</gadget>
<output>600</output>

<gadget id="calculator">12 / 600</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">400 * (1/50)</gadget>
<output>8</output>

<gadget id="calculator">8 + 12</gadget>
<output>20</output>

<result>20</result>