A project can be completed in 41 days by 50 workers. After 5 days of work, the work efficiency has increased (1/5), and after 5 days of work, the work efficiency has been improved on the new basis (1/4). How much in advance? finished?
一项工程50个工人41天可做完，做了5天后，工作效率提高了(1/5)，再做5天后，工作效率在新的基础上再提高(1/4)，请问提前几天做完？
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">1 / 41</gadget>
<output>1/41 = around 0.02439</output>

<gadget id="calculator">(1/41) * 5</gadget>
<output>5/41 = around 0.121951</output>

<gadget id="calculator">1 / 5</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">(1/41) * (6/5) * 5</gadget>
<output>6/41 = around 0.146341</output>

<gadget id="calculator">1 - (5/41) - (6/41)</gadget>
<output>30/41 = around 0.731707</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(1/41) * (6/5) * (5/4)</gadget>
<output>3/82 = around 0.036585</output>

<gadget id="calculator">(30/41) / (3/82)</gadget>
<output>20</output>

<gadget id="calculator">41 - 10 - 20</gadget>
<output>11</output>

<result>11</result>