If A and B cooperate to complete a project in 8 days, if A is allowed to work alone for 6 days, and then B works alone for 9 days to complete the task. How many days does it take for B to do this project alone?
一项工程，甲、乙合作8天完成，如果让甲先独做6天，然后乙再独做9天完成任务．求乙独做这项工程要多少天？
<gadget id="calculator">6 / 8</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">9 - 6</gadget>
<output>3</output>

<gadget id="calculator">(1/4) / 3</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / (1/12)</gadget>
<output>12</output>

<result>12</result>