A project can be completed in 8 hours by A alone, and 12 hours by B alone. Now how many hours will A and B work together to complete the whole project (5/8).
一项工程，甲独干需要8小时完成，乙独干用12小时完成，现在甲、乙合干多少小时完成全工程的(5/8)．
<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<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>5/24 = around 0.208333</output>

<gadget id="calculator">(5/8) / (5/24)</gadget>
<output>3</output>

<result>3</result>