The existing 300 grams of sugar water with 20% sugar content, how many grams of sugar do you need to add to make sugar water with 40% sugar content?
现有含糖20%的糖水300克，要变成含糖40%的糖水，需要加糖多少克？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(4/5) / (3/5)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">300 * (4/3)</gadget>
<output>400</output>

<gadget id="calculator">400 - 300</gadget>
<output>100</output>

<result>100</result>