A project is to be done by a team alone. Team A will take 20 days, and team B will take 30 days. First, team A will do it alone. After a few days, in order to complete the task ahead of schedule, team B and team A will jointly do it It took 14 days from start to finish. How many days did Team A and Team B work together?
一项工程，由一个队单独做，甲队要20天，乙队要30天，先由甲队单独做，做了几天后，为了提前完成任务，由乙队和甲队合做，这样从开始到完工共用了14天，甲乙两队合做了多少天？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 14</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

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

<gadget id="calculator">(3/10) / (1/30)</gadget>
<output>9</output>

<result>9</result>