It takes 20 days to build a road, and it takes 20 days for engineering team A to repair it alone, and 30 days for engineering team B to repair it alone. First, A alone repairs it in 5 days, and then the two engineering teams A and B jointly repair it. How many days will it take to complete?
修一条路，甲工程队单独修需20天，乙工程队单独修需30天，先由甲单独修5天，再由甲、乙两个工程队合修，还需多少天完成？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 5</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(1/20) + (1/30)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(3/4) / (1/12)</gadget>
<output>9</output>

<result>9</result>