A certain engineering team completed the old building renovation project in 20 days, which was ahead of schedule (1/9), how many days ahead of schedule.
某工程队用20天时间完成了旧楼改造工程，比计划时间提前了(1/9)，提前了多少天．
<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 - (1/9)</gadget>
<output>8/9 = around 0.888889</output>

<gadget id="calculator">20 / (8/9)</gadget>
<output>45/2 = around 22.5</output>

<gadget id="calculator">(45/2) - 20</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>