If a product is sold after a 20% price reduction, a 12% profit can still be obtained (profit = selling price - cost price). What is the profit margin (profit as a percentage of cost) before the price of the product is reduced?
某件商品降价20%后出售仍可获得12%的利润(利润=售出价-成本价)．则该商品降价前的利润率(利润占成本的百分数)是多少．
<gadget id="calculator">12 / 100</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">1 + (3/25)</gadget>
<output>28/25 = around 1.12</output>

<gadget id="calculator">1 * (28/25)</gadget>
<output>28/25 = around 1.12</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(28/25) / (4/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">(7/5) - 1</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 1</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>