There is a hot spring swimming pool with spring water gushing out from the bottom of the pool. To drain the full pool, 10 pumps need to work for 8 hours, and 9 pumps need to work for 9 hours. does not increase), how many pumps are needed to pump water out.
有一个温泉游泳池，池底有泉水不断涌出，要想抽干满池的水，10台抽水机需工作8小时，9台抽水机需工作9小时，为了保证游泳池水位不变(池水既不减少，也不增多)，则向外抽水的抽水机需多少台．
<gadget id="calculator">9 * 9</gadget>
<output>81</output>

<gadget id="calculator">10 * 8</gadget>
<output>80</output>

<gadget id="calculator">81 - 80</gadget>
<output>1</output>

<result>1</result>