A piece of work is completed in 20 days in collaboration with A and B. First, A will do it for 16 days, and then B will do it for 4 days. There is still (3/5) left to be done, and A will do it alone. How many days will it be done?
一件工作，甲乙合作20天完成，先由甲做16天，再由乙做4天，还剩(3/5)没有做完，由甲单独做，几天做完？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 4</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (3/5) - (1/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">16 - 4</gadget>
<output>12</output>

<gadget id="calculator">(1/5) / 12</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">1 / (1/60)</gadget>
<output>60</output>

<result>60</result>