The original price of a woolen sweater is 200 yuan, and now it is sold at a 20% discount because of a promotion in the store. How much is this woolen sweater cheaper than the original price?
一件羊毛衫的原价是200元，现因商店搞促销活动打八折出售，这件羊毛衫比原价便宜了多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">200 * (4/5)</gadget>
<output>160</output>

<gadget id="calculator">200 - 160</gadget>
<output>40</output>

<result>40</result>