There are 80 grams of salt water with a concentration of 12%. If 400 grams of water are added, what is the concentration of the new salt water?
有浓度为12%的盐水80克，若再加水400克，新盐水的浓度是多少？
<gadget id="calculator">12 / 100</gadget>
<output>3/25 = around 0.12</output>

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

<gadget id="calculator">(3/25) / 480</gadget>
<output>1/4_000 = around 0.00025</output>

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

<gadget id="calculator">80 * (1/4_000) * 1</gadget>
<output>1/50 = around 0.02</output>

<result>1/50 = around 0.02</result>