A project can be completed by A alone in 10 days. If A does it on the first day, and B does it on the second day, and do it alternately in this way, it will happen to be completed in an integer number of days. If B does it on the first day, and A does it on the second day, and do it alternately in this way, it will take more (1/3) days to complete than the last time. How many days can this project be completed by B alone?
一项工程，甲单独做10天可以完成．如果第一天甲做，第二天乙做，这样轮流交替做，也恰好用整数天完成．如果第一天乙做，第二天甲做，这样轮流交替做，比上次轮流做要多(1/3)天才能完成．这项工程由乙独做几天可以完成？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 + (1/3)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">(1/10) / (4/3)</gadget>
<output>3/40 = around 0.075</output>

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

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