If exactly 216 people sign up for a charter flight, Leisure World Travel Agency charges $286/person. However, if more than 216 people sign up for the flight (assume this is the case), then each fare is reduced by $1 for each additional person. Determine how many passengers will result in a maximum revenue for the travel agency. Hint: Let x denote the number of passengers above 216. Show that the revenue function R is given by R(x) = (216 + x)(286 − x).