The purchase price of a product is 500 yuan, and the price is 750 yuan. If the product is sold at 20% off the price, what is the profit margin of this product?
某商品的进价是500元，标价是750元，若此商品按标价的8折出售，则此商品的利润率是多少．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">750 * (4/5)</gadget>
<output>600</output>

<gadget id="calculator">600 - 500</gadget>
<output>100</output>

<gadget id="calculator">100 / 500</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>