A project can be completed by team A alone in 20 days, and team B alone can complete it every day (1/30). If Team A works alone for 4 days first, and Team B does the rest alone, how many days does Team B need to complete?
一项工程，甲队单独做要20天完成，乙队单独做每天完成(1/30)．如果甲队先单独做4天，剩下部分由乙队独做，乙队需多少天完成？
<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 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(4/5) / (1/30)</gadget>
<output>24</output>

<result>24</result>