A piece of engineering, A and B cooperate to complete in 6 days. If A works alone in 3 days to complete the whole project (1/5), how many days can B work alone to complete it?
一件工程，甲乙合做6天完成．甲单独做3天完成全工程的(1/5)，乙单独做多少天可以完成？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / 3</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/6) - (1/15)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / (1/10)</gadget>
<output>10</output>

<result>10</result>