How much should I pay ?   Let me see . A roasted duck is $ 25 . A plate of pork is $ 6.50 . A bowl of beef is $ 7 . Two bottles of beer are $ 4 . That's a total of $ 42.50 .   Here is $ 50 . Keep the change , please .   Oh , sorry sir . We take no tips here . Thank you all the same . 