The factory is going to make a batch of garments. If workshop A does it alone, it will take 20 days to complete it, and if workshop B does it alone, it will take 30 days to complete it. How many days will it take for the two teams to work together?
工厂要做一批服装，如果甲车间单独做要20天完成，如果乙车间单独做要30天完成．两队合做，需要几天完成？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</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">1 / (1/12)</gadget>
<output>12</output>

<result>12</result>