The original price of a bicycle is 400 yuan, and a 20% discount is offered during the "Six Day" Children's Day. Xiaoyu bought a bicycle during the event. How much is the bicycle that Xiaoyu bought cheaper than the original price?
一种自行车原价卖400元，在"六一"儿童节期间打八折优惠活动，小宇在活动期间买了一辆，小宇买的自行车比原价便宜了多少钱？
<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">400 * (1/5)</gadget>
<output>80</output>

<result>80</result>