To build a canal, team A will repair this canal every day (1/20), team B will repair this canal every day (1/30), how many days will the two teams work together to complete the repair.
修一条水渠，甲队每天修这条水渠的(1/20)，乙队每天修这条水渠的(1/30)，两队合修多少天修完．
<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>