It takes 12 days to repair a road by Team A alone, and 15 days to complete it if Team B alone repairs it. Now, how many days will it take for Team A and Team B to repair it together?
修一条公路，如果由甲队单独修，需要12天完成，如果由乙队单独修需要15天完成，现在甲乙两队合修，需要多少天完成？
<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>