Mom went to the New Century Supermarket to buy a bottle of laundry detergent and a bucket of salad oil. Laundry liquid 21.20 yuan/bottle, salad oil 58.80 yuan/bottle. She gave 100 yuan, how much should the cashier get back?
妈妈到新世纪超市买了一瓶洗衣液和一桶色拉油．洗衣液21.20元/瓶，色拉油58.80元/瓶．她给了100元，收银员应该找回多少钱？
<gadget id="calculator">21.2 + 58.8</gadget>
<output>80</output>

<gadget id="calculator">100 - 80</gadget>
<output>20</output>

<result>20</result>