A project can be completed by A alone in 10 days and B by himself in 20 days. Now A and B cooperate, A rests for 1 day, and B rests for 5 days. How many days will it take to complete this project?
一项工程，甲独做10天完成，乙独做20天完成．现在甲乙合作，甲休息1天，乙休息5天，完成这项工程需要多少天？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 5</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/10) + (1/4)</gadget>
<output>27/20 = around 1.35</output>

<gadget id="calculator">(1/10) + (1/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(27/20) / (3/20)</gadget>
<output>9</output>

<result>9</result>