road, if two engineering teams A and B work together, it will take 6 days; if B engineering team repairs it alone, it will take 9 days, if A engineering team repairs it alone, how many days will it take?
一条公路，如果甲、乙两个工程队一起修，需要6天；如果乙工程队单独修，需要9天，如果甲工程队单独修，需要多少天？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/6) - (1/9)</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">1 / (1/18)</gadget>
<output>18</output>

<result>18</result>