batch of goods can be shipped by car A alone in 8 days, and by car B alone in 12 days. After the two vehicles are transported together for several days, the rest will be transported by A vehicle alone, and it will be completed in 3 days. How many days have the two cars been transported together?
一批货物，甲车独运8天可以运完，乙车独运12天可以运完．两车合运若干天后，剩下的由甲车单独运，3天完成．两车合运了多少天．
<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>