A piece of clothing costs 200 yuan, and the shopping mall sells it with a 20% discount. How much can it be cheaper to buy this piece of clothing?
一件衣服200元，商场打八折销售，买这件衣服能便宜多少元．
<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>