It takes 20 days for team A to complete a project alone, and 30 days for team B. If the two teams cooperate, how many days will it take to complete the task?
单独完成一项工程，甲队要20天，乙队要30天，两队合作，需要多少天完成任务？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

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

<result>12</result>