A product is sold with a 20% discount, which is 84 yuan cheaper. How much is the original price?
一件商品降价8折出售，便宜了84元，原价是多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">84 / (1/5)</gadget>
<output>420</output>

<result>420</result>