There is a well from which spring water gushes out continuously, and the amount of water gushing out every minute is equal. If 3 pumps are used to pump water, the water can be pumped in 36 minutes; if 5 pumps are used, it can be pumped in 20 minutes. If there are 8 water pumps, how many minutes can they be pumped out?
有一口水井，连续不断涌出泉水，每分钟涌出的水量相等．如果使用3台抽水机来抽水，36分钟可以抽完；如果使用5台抽水机，20分钟抽完．若有8台抽水机，多少分钟可以抽完？
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">36 * 3</gadget>
<output>108</output>

<gadget id="calculator">108 - 100</gadget>
<output>8</output>

<gadget id="calculator">36 - 20</gadget>
<output>16</output>

<gadget id="calculator">8 / 16</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * 20</gadget>
<output>10</output>

<gadget id="calculator">100 - 10</gadget>
<output>90</output>

<gadget id="calculator">8 - (1/2)</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">90 / (15/2)</gadget>
<output>12</output>

<result>12</result>