There are 200 kilograms of brine with a salt content of 10%, and now you want to make the salt content of the brine into 20%, how many grams of salt should be added?
有含盐10%的盐水200千克，现在想使盐水的含盐率变为20%，那么要加入多少克盐？
<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">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">(9/10) / (4/5)</gadget>
<output>9/8 = around 1.125</output>

<gadget id="calculator">200 * (9/8)</gadget>
<output>225</output>

<gadget id="calculator">225 - 200</gadget>
<output>25</output>

<result>25</result>