project can be completed in 15 days by A alone. If A works in 5 days first, and B alone needs 8 days to complete the rest, how many days will it take for B to complete the project alone?
一项工程，甲单独做15天完成，如果甲先做5天，余下的工程由乙独做还需8天完成，那么由乙单独完成这项工程要多少天．
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 5</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) / 8</gadget>
<output>1/12 = around 0.083333</output>

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

<result>12</result>