There is a project in the "Banan Expressway" that has started construction. Team A will complete it in 30 days alone, and Team B will complete it every day (1/20). If Team B works alone for 4 days, the rest will be completed by Team A. Working alone, how many days does Team A need to complete?
已开工建设的"巴南高速"中有一项工程，甲队独做要30天完成，乙队独做每天完成(1/20)，如果乙队先独做4天，剩下部分由甲队独做，甲队需要多少天完成？
<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>