A jacket, originally priced at 700 yuan, now only costs 20% off, how much cheaper than the original price.
一件上衣，原价700元，现在只花八折的钱，比原价便宜了多少元钱．
<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">700 * (1/5)</gadget>
<output>140</output>

<result>140</result>