A certain project can be completed in 12 days if A alone takes 20 days. Now A will do it alone for 16 days, and then A and B will finish it together. How many days will it take?
某项工程，甲单独做需要20天，如果与乙合作12天就可以完成．现在由甲单独做16天，然后由甲乙合作做完．还需要几天时间？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 16</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(1/5) / (1/12)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>