Travel type sample round-trip fares from new york to london first-class air fare $754.30 first-class ship fare $775.20 regular economy air fare $440.80 tourist class ship fare $408.00 peak season economy air fare $526.30 peak season tourist class ship fare $470.25 14- to 21-day excursion air fare $331.00 30-day excursion ship fare $345.95 charter group (25 persons or more) air fare $331.00 charter group (25 persons or more) ship fare $306.00 what percentage increase occurs in the price of a round-trip economy plane ticket from new york to london by electing to go first-class as opposed to going on the regular economy class?