During the New Year's Day, the shopping mall held a discount promotion activity, and a certain brand of TV set was sold at a 20% discount. Teacher Yang bought a TV set with an original price of 3,850 yuan during the event. How much cheaper than usual?
商场在元旦期间进行打折促销活动，某品牌电视机打八折出售，杨老师在活动期间购买了一台原价3850元的电视机，比平时便宜了多少钱？
<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">3_850 * (1/5)</gadget>
<output>770</output>

<result>770</result>