If 33 kg of salt water containing 20% salt is made into salt water containing 25% salt, how much salt should be added in kg?
把含盐20%的盐水33kg，制成含盐25%的盐水，需加盐多少kg．
<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">25 / 100</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(4/5) / (3/4)</gadget>
<output>16/15 = around 1.066667</output>

<gadget id="calculator">33 * (16/15)</gadget>
<output>176/5 = around 35.2</output>

<gadget id="calculator">(176/5) - 33</gadget>
<output>11/5 = around 2.2</output>

<result>11/5 = around 2.2</result>