There is a pool full of water, and spring water gushes out continuously from the bottom of the pool. The amount of water that gushes out every minute is equal. It takes 10 pumps to drain the water in 20 hours, and 15 pumps to drain the water in 10 hours. How much is it to use 25 pumps? The water can be drained in hours.
有一满水池，池底有泉水不断涌出，每分钟涌出的水量相等，用10部抽水机20小时可以把水抽干，用15部抽水机10小时可以把水抽干，那么用25部抽水机多少小时可以把水抽干．
<gadget id="calculator">10 * 20</gadget>
<output>200</output>

<gadget id="calculator">15 * 10</gadget>
<output>150</output>

<gadget id="calculator">200 - 150</gadget>
<output>50</output>

<gadget id="calculator">20 - 10</gadget>
<output>10</output>

<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<gadget id="calculator">5 * 20</gadget>
<output>100</output>

<gadget id="calculator">200 - 100</gadget>
<output>100</output>

<gadget id="calculator">25 - 5</gadget>
<output>20</output>

<gadget id="calculator">100 / 20</gadget>
<output>5</output>

<result>5</result>