To build a road, if team A works alone, it will complete the task in 12 days; if team B repairs it alone, it will finish the task in 15 days. If the two teams work together, how many days can it be completed?
修一条公路，如果甲队单独修，12天完任务；如果乙队单独修，15天完任务．如果两队合修，多少天能修完？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/12) + (1/15)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 / (3/20)</gadget>
<output>20/3 = around 6.666667</output>

<result>20/3 = around 6.666667</result>