There is a project to be completed in 20 days, according to the new construction plan, it can be completed 10% ahead of time; if more advanced equipment is added, then the work efficiency can be increased by 20%, and the work continues like this. How many days will this project be completed?
有一项工程计划20天完成，按新的施工方案可以提前10%的时间完成；如果再增加先迸的设备，那么还可以提高20%的工作效率，照这样干下去．这项工程多少天就可以完成？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</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">20 * (9/10) * (5/6)</gadget>
<output>15</output>

<result>15</result>