How many grams of water is added to 400 grams of 12% salt water to make the concentration 10%.
浓度为12%的盐水400克，加入多少克水后浓度变为10%．
<gadget id="calculator">12 / 100</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(3/25) / (1/10)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">400 * (6/5)</gadget>
<output>480</output>

<gadget id="calculator">480 - 400</gadget>
<output>80</output>

<result>80</result>