A project can be completed by A alone in 6 days and B by himself in 9 days. A firstly completes (1/3) of the entire project, and B completes the rest, how many days will it take?
一件工程，甲独做6天完成，乙独做9天完成．甲先独做了全部工程的(1/3)，余下的由乙单独完成，还需要多少天？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

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

<result>6</result>