There is a glass of 240 grams of sugar water containing 20% sugar. After adding some sugar, the ratio of sugar to sugar water is 5:21. How many grams of sugar were added?
现有一杯含糖20%的糖水240克，加入一些糖后，糖与糖水的比是5：21．加进了多少克糖？
<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">240 * (4/5)</gadget>
<output>192</output>

<gadget id="calculator">5 / 21</gadget>
<output>5/21 = around 0.238095</output>

<gadget id="calculator">1 - (5/21)</gadget>
<output>16/21 = around 0.761905</output>

<gadget id="calculator">192 / (16/21)</gadget>
<output>252</output>

<gadget id="calculator">252 - 240</gadget>
<output>12</output>

<result>12</result>