One job can be done by A alone in 8 hours and B by himself in 12 hours. How many hours can the two work together to complete?
一件工作甲单独做8小时可以完成，乙单独做12小时可以完成．两人合作多少小时可以完成．
<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">1 / (5/24)</gadget>
<output>24/5 = around 4.8</output>

<result>24/5 = around 4.8</result>