To configure a kind of pesticide, the mass ratio of liquid medicine to water is 1:500. If 800kg of water is used, how many kg of liquid medicine should be added?
配置一种农药，所需药液与水的质量比是1：500，如果用800kg的水，那么需要加入药液多少kg？
<gadget id="calculator">1 / 500</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">800 * (1/500)</gadget>
<output>8/5 = around 1.6</output>

<result>8/5 = around 1.6</result>