It takes 30 days to complete the production task of 3600 parts if it is done by A alone; if it takes 20 days to complete it for B alone, how many days can the task be completed if the two cooperate now?
3600个零件的生产任务，如果给甲独做需要30天完成；如果给乙独做需要20天完成，现在两人合作，多少天可以完成任务？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/30) + (1/20)</gadget>
<output>1/12 = around 0.083333</output>

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

<result>12</result>