Read and listen to a dialogue or a passage twice and choose the best answer. The guest has finished his lunch and has some questions about the bill. The waitress will explain the bill and help to pay it. Customer: l'm full. Could I have my bill, please? Staff: Certainly, sir. Just a minute, please. Here is your bill, sir. The total is RMB 648. Customer: Oh, that seems too big. Perhaps there is a mistake. Can you show me the bill? Staff: Sure, here you are. Customer: Could you explain it to me? Staff: Certainly, sir. The first item is for dishes you ordered, the steamed seafood, RMB 150, Fried Lobster, RMB 100, Chicken with Bean Sauce, RMB 68, Pork with Broccoli, RMB 90, Hot and Sour Soup, RMB 42. Customer: Right. How about drinks? Staft: Yes. The second item is for the drinks. A bottle of Qingdao Beer, RMB 60, a bottle of mineral water, RMB 30. The green tea you had is free. Customer: So that makes only a total of 540. Staff: Yes, sir. You re right. But there is a 20% service charge. So the total comes to 648. Customer: Oh, I see. Could you give me any discount? Staff: l'm afraid we can't. Customer: Could I pay by credit card? Staff: Certainly, sir. Since you're staying in our hotel, you can just sign your bill. Customer: Good idea. l'll do that then. Staff: Thank you very much, sir. Have a nice day. Question3: How much is the service charge?