A project can be completed in 15 days by team A alone, 12 days by team B alone, and 3 days after team B alone, team A joins in cooperation, how many days will it take to complete the work?
一项工程，甲队单独做要15天完成，乙队单独做12天完成，乙队独做3天后，甲队加入一起合作，还要多少天才能完成这项工作？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 3</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

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

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

<gadget id="calculator">(3/4) / (3/20)</gadget>
<output>5</output>

<result>5</result>