A project, if team A works alone in 5 days can complete the whole project (1/3); if team B and C work together in 12 days, the whole project can be completed. How many days can three teams work together to complete the whole project?
一项工程，如果甲队单独做5天可以完成全工程的(1/3)；如果乙、丙两队合做12天可以完成全工程．三队合做多少天可以完成全工程？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / 5</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>