It takes 12 hours for A to complete a job alone, and 3 hours for A and B to complete it together (July 14), how many hours does it take for B to complete it alone?
一项工作甲单独完成要12小时，甲乙合做3小时完成(7/14)，乙单独完成要几小时？
<gadget id="calculator">7 / 14</gadget>
<output>1/2 = around 0.5</output>

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