It takes 8 days for A and B to complete a job together. If it takes 12 days for B to complete the work alone, the two work together at the beginning of the work. After a period of cooperation, B leaves because of other tasks, and A continues to do the rest of the work. A completes the task in another 3 days. How many days have you worked together?
一件工作，甲、乙合做需要8天完成．如果由乙单独做需要12天完成，开工时两人合做，合做一段时间后，乙因另有任务离开了，余下的工作由甲继续做，甲又做了3天完成任务，两人合做了几天？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

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

<gadget id="calculator">(1/8) - (1/12)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">(1/24) * 3</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 - (1/8)</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">(7/8) / (1/8)</gadget>
<output>7</output>

<result>7</result>