A and B work together to complete a project in 6 days. The efficiency ratio of A and B is 2:1. How many days does it take for A to complete it alone?
甲、乙合做一项工程要6天完成，甲、乙的效率比2：1，甲独做多少天完成．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(1/6) * (2/3)</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 / (1/9)</gadget>
<output>9</output>

<result>9</result>