There is a part of water in the swimming pool of Qingyang Swimming Pool. There is one water inlet pipe and three drain pipes. If one drain pipe and one water inlet pipe are opened, it will take 30 hours to drain the water from the pool. If two drain pipes and one water inlet pipe are opened , it will take 10 hours to drain the water in the pool, then, if all three drain pipes and one water inlet pipe are opened, how many hours will it take to drain the water in the pool?
青阳游泳馆游泳池里有一部分水，有一个进水管和3个排水管，如果打开一个排水管和一个进水管，需要30小时把水池的水排完，如果打开2个排水管和一个进水管，则需要10小时把水池的水排完，那么，如果把3个排水管和一个进水管都打开，则需要几小时把水池的水排完？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/10) - (1/30)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 3</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/15) - (1/30)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/5) - (1/30)</gadget>
<output>1/6 = around 0.166667</output>

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

<result>6</result>