A and B work together to complete a job in 6 hours, A alone can complete it in 12 hours, and B alone can complete it in how many hours.
一件工作，甲、乙合作6小时完成，甲单独做要12小时完成，乙单独做要多少小时可以完成．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/6) - (1/12)</gadget>
<output>1/12 = around 0.083333</output>

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

<result>12</result>