manuscript needs to be typed, A alone typed 4 hours to type (1/3) of this manuscript, B then typed for another 2 hours, typed (1/4) of this manuscript, and A and B jointly typed the rest , how many hours will it take?
一份稿件需要打字，甲单独打4小时打了这份稿件的(1/3)，乙接着又打了2小时，打了这份稿件的(1/4)，剩余的甲、乙共同打，还需几小时？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/3) - (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">(1/3) / 4</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/4) / 2</gadget>
<output>1/8 = around 0.125</output>

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

<gadget id="calculator">(5/12) / (5/24)</gadget>
<output>2</output>

<result>2</result>