There are two water inlet pipes on a pool, if pipe A is opened alone, the empty pool can be filled in 10 hours; if pipe B is opened alone, the empty pool can be filled in 15 hours. Now two water pipes A and B discharge water at the same time, how many hours can the pool be filled? (formerly an empty pool)
一个水池上有两个进水管，单开甲管，10小时可把空池注满，单开乙管，15小时可把空池注满．现在甲乙两根水管同时放水，几小时可以把水池放满？(原是空池)
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) + (1/15)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / (1/6)</gadget>
<output>6</output>

<result>6</result>