There are two water pipes A and B installed in a pool. It takes 8 hours to fill the empty pool with the A water pipe alone, and 12 hours to fill the empty pool with the B water pipe alone. Opening both water pipes at the same time, how many hours can the empty pool be filled?
一个水池安有甲乙两个水管，单开甲水管8小时可以把空池注满，单开乙水管12小时可以把空池注满，同时打开两个水管，多少小时可以把空池注满？
<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>