There are 300 grams of brine with a salt content of 45%, and to make brine with a salt content of 15%, how many grams of water should be added?
有含盐45%的盐水300克，配制成含盐15%的盐水，需加水多少克？
<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(9/20) / (3/20)</gadget>
<output>3</output>

<gadget id="calculator">300 * 3</gadget>
<output>900</output>

<gadget id="calculator">900 - 300</gadget>
<output>600</output>

<result>600</result>