Add 30 grams of sugar and how many grams of water to 20% sugar water, and the sugar water will be as sweet as before.
在含糖20%的糖水中加入30克糖和多少克水，糖水和原来一样甜．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">30 / (1/5)</gadget>
<output>150</output>

<gadget id="calculator">150 - 30</gadget>
<output>120</output>

<result>120</result>