How many grams of water are added to 400 g of sugar water with a concentration of 10% to obtain sugar water with a concentration of 8%.
往浓度为10%，重量为400克的糖水中加入多少克水，就可以得到浓度为8%的糖水．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">400 * (1/10)</gadget>
<output>40</output>

<gadget id="calculator">8 / 100</gadget>
<output>2/25 = around 0.08</output>

<gadget id="calculator">40 / (2/25)</gadget>
<output>500</output>

<gadget id="calculator">500 - 400</gadget>
<output>100</output>

<result>100</result>