It takes 6 hours for A to do a job alone, and 4 hours for B to do it alone. After A finishes (1/2), how many hours will it take for the remaining two to finish it?
一件工作，甲单独做要6小时，乙单独做要用4小时，甲做完(1/2)后，剩下的两人合作，还要几小时才能完成？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

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

<gadget id="calculator">(1/6) + (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">(1/2) / (5/12)</gadget>
<output>6/5 = around 1.2</output>

<result>6/5 = around 1.2</result>