In one project, Master Cai improved the working method after finishing half of it, which increased the efficiency by 20%. As a result, it was completed two days earlier than the original plan. How many days was the original construction period?
有一项工程，蔡师傅做了一半后改进了工作方法，使得效率提高了20%，结果比原计划提前两天完成，那么原计划的工期是多少天？
<gadget id="calculator">6 / 5</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1 / (6/5)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">1 - (5/6)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">2 / (1/6)</gadget>
<output>12</output>

<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<result>24</result>