How much water is needed to prepare brine with a salt content of 20% from 20 grams of salt?
用20克盐去配制含盐率为20%的盐水，需要多少水．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 / (1/5)</gadget>
<output>100</output>

<gadget id="calculator">100 - 20</gadget>
<output>80</output>

<result>80</result>