To prepare a pesticide, the ratio of powder to water is 1:200. The current powder is 2.5 kg. How much water should be added to prepare this pesticide?
要配置一种农药，药粉和水的比是1：200，现在的药粉2.5千克，配制这种农药需加水多少千克？
<gadget id="calculator">2.5 / 1</gadget>
<output>2.5</output>

<gadget id="calculator">2.5 * 200</gadget>
<output>500</output>

<result>500</result>