Two teams excavate the canal. Team A will complete the excavation in 8 days alone, and team B will complete the excavation alone in 12 days. Now, after the two teams dig for a few days at the same time, team B will be transferred away, and team A will complete the rest within 3 days. How many days did Team B work? (column solution)
两队开挖运河，甲队单独挖要8天完成，乙队单独挖要12天完成，现在两队同时挖了几天后，乙队调走，余下的由甲队在3天内完成，问乙队干了几天？(列式解答)
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/8) * 3</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">1 - (3/8)</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/8) + (1/12)</gadget>
<output>5/24 = around 0.208333</output>

<gadget id="calculator">(5/8) / (5/24)</gadget>
<output>3</output>

<result>3</result>