Take 200 grams of brine with a salt content of 20%, and how many grams of salt can be added to increase the salt content to 25%.
含盐率为20%的盐水200克，再加入多少克盐就能使含盐率提高到25%．
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 200</gadget>
<output>50</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">200 * (1/5)</gadget>
<output>40</output>

<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">10 / (3/4)</gadget>
<output>40/3 = around 13.333333</output>

<result>40/3 = around 13.333333</result>