If 100 grams of sugar water containing 10% sugar is to be converted into sugar water containing 28% sugar, how many grams of sugar should be added?
100克含糖10%的糖水要变成含糖28%的糖水，需要加多少克糖？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">28 / 100</gadget>
<output>7/25 = around 0.28</output>

<gadget id="calculator">1 - (7/25)</gadget>
<output>18/25 = around 0.72</output>

<gadget id="calculator">(9/10) / (18/25)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">100 * (5/4)</gadget>
<output>125</output>

<gadget id="calculator">125 - 100</gadget>
<output>25</output>

<result>25</result>