A person buys a product with D yuan and C points, and gives 20 yuan to the salesperson. The salesperson mistook it as C yuan and D points, so he gave the customer 4.88 yuan. So how much should the salesperson give the customer based on the correct price?
一个人买了D元C分的商品，交给营业员20元，营业员误看成C元D分，于是找给顾客4.88元，那么按正确的标价营业员应找给顾客多少元？
<gadget id="calculator">20 - 12.15</gadget>
<output>7.85</output>

<result>7.85</result>