A project, if A and B work together, (1/3) of the project will be completed in 2 days. If A works alone, the project will be completed in 10 days. Now if B does it alone, how many days can the whole project be completed?
一项工程，如果甲、乙合干，2天完成这项工程的(1/3)．如果甲单独干，10天完成这项工程．现在由乙单独干，几天可以完成全部工程？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / 2</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/6) - (1/10)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / (1/15)</gadget>
<output>15</output>

<result>15</result>