A project is completed in 15 days by teams A and B. If team A works in 5 days and team B works in 3 days, only 7/30 of the project can be completed. How many days will it take for team B to complete the entire project alone?
一项工程，甲、乙两队合作15天完成，若甲队做5天，乙队做3天，只能完成工程的(7/30)，乙队单独完成全部工程需要几天？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">7 / 30</gadget>
<output>7/30 = around 0.233333</output>

<gadget id="calculator">(1/15) * 3</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(7/30) - (1/5)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) / 2</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/15) - (1/60)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / (1/20)</gadget>
<output>20</output>

<result>20</result>