Add 12 grams of salt and 28 grams of water to 30% salt water. What is the percentage of salt in this salt water?
在含盐30%的盐水中，加入12克盐28克水，这盐水含盐百分比是大于多少
<gadget id="calculator">12 + 28</gadget>
<output>40</output>

<gadget id="calculator">12 / 40</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(3/10) * 1</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>