For a manuscript, it takes 8 hours for typists A and B to finish typing it together, and 12 hours for typist B to finish it alone. how many hours.
一份稿件，甲乙两个打字员合作打完需要8小时，乙打字员单独打完需要12小时，实际情况是两人先合作了2小时后，剩下的由乙打字员独自完成，还需多少小时．
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/8) * 2</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 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(3/4) / (1/12)</gadget>
<output>9</output>

<result>9</result>