It takes 12 days for Team A to complete a project alone, and 15 days for Team B to complete it alone. How many days will it take for Team A and Team B to complete it together?
一项工程，甲队单独完成需要12天，乙队单独完成需要15天，甲、乙合做要多少天完成？
<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>