A job can be done by A alone in 12 hours. Now AB and AB cooperate for 2 hours, and B spends another 5.5 hours to complete the remaining work. If B does all the work, how many hours will it take?
一件工作，A单独做12小时完成．现在AB两个合作2小时，剩下的工作，B又用了5.5小时完成，如果这件工作全部由B来做，需几小时？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 2</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 - (1/6)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">2 + 5.5</gadget>
<output>7.5</output>

<gadget id="calculator">(5/6) / 7.5</gadget>
<output>0.111111</output>

<gadget id="calculator">1 / 0.111111</gadget>
<output>9.000009</output>

<result>9.000009</result>