The price of a coat after a 20% discount is 80 yuan. How much is this coat cheaper than the original price?
一件上衣打八折出售后的价钱是80元，这件上衣比原价便宜多少钱？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">80 / (4/5)</gadget>
<output>100</output>

<gadget id="calculator">100 - 80</gadget>
<output>20</output>

<result>20</result>