If 80 grams of salt water with a concentration of 20% is to be converted into salt water with a concentration of 75%, how many grams of salt should be added?
现有浓度为20%的盐水80克，如果要变成浓度为75%的盐水，需要加入多少克盐？
<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">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(4/5) / (1/4)</gadget>
<output>16/5 = around 3.2</output>

<gadget id="calculator">80 * (16/5)</gadget>
<output>256</output>

<gadget id="calculator">256 - 80</gadget>
<output>176</output>

<result>176</result>