A project can be completed by team A in 12 days and by team B in 15 days. Now, after a few days of cooperation between teams A and B, team B is transferred away, and team A will complete the rest in 3 days alone. How many days did team B actually do?
一项工程，由甲队独做需12天完成，乙队独做需15天完成．现甲、乙两队合做几天后，乙队调走，剩下的由甲队独做3天完成，乙队实际做了多少天？
<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">(1/12) + (1/15)</gadget>
<output>3/20 = around 0.15</output>

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

<result>5</result>