The swimming pool in Chengbei Stadium has two water outlets, A and B. It takes 8 hours to drain the water from the pool when A is opened alone, and it takes 10 hours to drain the water from the whole pool when only the B outlet is opened. If two water outlets are opened at the same time, how many hours will it take to drain the whole pool?
城北体育场的游泳池共有甲乙两个出水口，单开甲出水口需8小时能将全池水放干，单开乙出水口需10小时才能将全池水放干．同时打开两个出水口，需要多少小时能将全池水放干？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/8) + (1/10)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">1 / (9/40)</gadget>
<output>40/9 = around 4.444444</output>

<result>40/9 = around 4.444444</result>