A project is completed by two teams, A and B, in 12 days. Now teams A and B work together for 4 days, and A will complete the rest of the project in 20 days. If the rest of the project is done by B alone, how many days will it take?
一项工程，由甲、乙两队合作12天完成．现在由甲、乙两队合作4天，余下的工程由甲独又用20天完成，如果余下的工程由乙队独做，需要多少天完成？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 4</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) / 20</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/12) - (1/30)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(2/3) / (1/20)</gadget>
<output>40/3 = around 13.333333</output>

<result>40/3 = around 13.333333</result>