To build a road, it takes 12 days to build 40% of its length. According to this calculation, how many days will it take for the rest?
修一条路，12天修完全长的40%，照这样计算，余下的需多少天？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(2/5) / 12</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(3/5) / (1/30)</gadget>
<output>18</output>

<result>18</result>