Add 100 grams of water to 400 grams of 5% salt water, what is the salt content of the salt water?
在5%的400克盐水中，加入100克水，这时盐水的含盐率是多少．
<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">400 * (1/20)</gadget>
<output>20</output>

<gadget id="calculator">400 + 100</gadget>
<output>500</output>

<gadget id="calculator">20 / 500</gadget>
<output>1/25 = around 0.04</output>

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

<gadget id="calculator">(1/25) * 1</gadget>
<output>1/25 = around 0.04</output>

<result>1/25 = around 0.04</result>