In order to create a green school, the students of the science club designed a pool that recycles the vegetable washing water from the school cafeteria to water the flowers. It is required to open the water inlet pipe alone for 3 hours to fill the pool, and open the outlet pipe for 4 hours to drain the water completely. After the pool was built, it was found that the pool was leaking. At this time, if the water inlet pipe and the water outlet pipe are opened at the same time, the pool can be filled for 14 hours. Then the pool is filled with water, and when the water inlet and outlet pipes are closed, how many hours will the water in the pool leak out.
为了创建绿色学校，科学俱乐部的同学设计了一个回收学校食堂的洗菜水来浇花的水池，要求单独开进水管3小时可把水池注满，单独打开出水管4小时排完满池水．水池建成后，发现水池漏水．这时，若同时打开进水管与出水管14小时才能把水池注满．则池水注满，并且关闭进水管与出水管时，经过多少小时池水会漏完．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/3) - (1/4)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 14</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">(1/12) - (1/14)</gadget>
<output>1/84 = around 0.011905</output>

<gadget id="calculator">1 / (1/84)</gadget>
<output>84</output>

<result>84</result>