Well, if he is only in town for a conference or meeting, and doesn't really feel a need to stay in the latest trendy Düsseldorf hotel at 200 euro a night + 50 euro for the meal and drinks, but instead opts to bed down in the Ibis Duisburg at 60 euro a night plus 6 euro for the Döner and beer, he will probably come out ahead financially. His trip seems too short for much sightseeing.