Two engineering teams, A and B, jointly build a project. It is known that the two teams cooperate to complete the project in exactly 6 days. If it takes 18 days for A to complete the project alone, how many days will it take for B to complete the project alone?
甲、乙两工程队共同修建一项工程，已知两队合作正好6天完成，如果甲队单独完成这项工程需要18天，那么乙队单独完成这项工程需要多少天．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 18</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">(1/6) - (1/18)</gadget>
<output>1/9 = around 0.111111</output>

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

<result>9</result>