A batch of parts can be completed in 8 days by A and B together, 4 days by A and B together, and the rest can be completed by B in 6 days. How many days will it take B to make this batch of parts alone?
一批零件，甲、乙合做8天可以完成，甲、乙合做4天，剩下的由乙6天完成，乙单独做这批零件要用多少天？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/8) * 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) / 6</gadget>
<output>1/12 = around 0.083333</output>

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

<result>12</result>