There are 240 grams of salt water with a salt content of 3%, how much is needed to make it a salt water with a salt content of 4%.
现有含盐3%的盐水240克，如果要使它含盐变成4%的盐水，需要多少．
<gadget id="calculator">3 / 100</gadget>
<output>3/100 = around 0.03</output>

<gadget id="calculator">4 / 100</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(3/100) / (1/25)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">240 * (3/4)</gadget>
<output>180</output>

<gadget id="calculator">240 - 180</gadget>
<output>60</output>

<result>60</result>