The original price of a piece of clothing is 200 yuan, but now it is sold at a 20% discount. How much is it cheaper?
一件衣服原价200元，现在打八折出售，便宜了多少元．
<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">200 * (1/5)</gadget>
<output>40</output>

<result>40</result>