Prepare a kind of salt water, the weight ratio of salt and water is 1:4, how much salt accounts for the salt water.
配制一种盐水，盐和水的重量比是1：4，盐占盐水的多少．
<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>