A project can be completed by A alone in 40 days and by B in 60 days. How many days will it take for them to cooperate to complete (1/2) of this project?
一件工程，甲独做40天完成，乙独做60天完成．他们合作完成这件工程的(1/2)，需要多少天？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/40) + (1/60)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">(1/2) / (1/24)</gadget>
<output>12</output>

<result>12</result>