An empty pool has two inlet pipes A and B and one drain pipe. It takes 5 minutes to fill the pool with pipe A alone, and it takes 10 minutes to fill the pool with pipe B alone. If the water in the pool is full, it takes 6 minutes to drain the drain. One time there was no water in the pool. After opening pipe A for several minutes, it was found that the drain pipe was not closed. Then the drain pipe was closed and pipe B was opened at the same time. After the same time, 1/4 of the pool was filled with water. If you continue to fill the pool, how long will it take in total?
一空水池有甲、乙两根进水管和一根排水管．单开甲管需5分钟注满水池，单开乙管需10分钟注满水池，满池水如果单开排水管需6分钟流尽．某次池中没有水，打开甲管若干分钟后，发现排水管未关上，随即关上排水管，同时打开乙管，又过了同样长的时间，水池的1/4注了水．如果继续注满水池，前后一共要花多少时间？
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(3/2) + (5/2)</gadget>
<output>4</output>

<result>4</result>