To build a road, Team A will complete the repair in 30 days alone, and Team B will complete the repair in 20 days alone. If the two teams work together, how many days will it take to finish?
修一条路，甲队单独修30天修完，乙队单独修20天修完．如果两队合修，需要几天修完？
<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>