There is a kind of pesticide, the medicine and water are prepared according to the ratio of 1:1500, there are 3 kilograms of medicine liquid, how many kilograms of water need to be added? (Solve with ratio)
有一种农药，用药和水按1：1500配制而成，现有3千克药液，需加多少千克水？(用比例解)
<gadget id="calculator">1 / 1_500</gadget>
<output>1/1_500 = around 0.000667</output>

<gadget id="calculator">3 / (1/1_500)</gadget>
<output>4_500</output>

<result>4_500</result>