Let x = number of persons in excess of 200
R(x) = revenue if x people go on the trip
R(x) = (price per ticket)(number of tickets)
R(x) = (600 - 2x)(x + 200)
= -2x2 + 200x + 120,000
The graph of the revenue function is a parabola opening downward. The revenue is maximized when
x = -200/(2(-2)) = 50. So, to maximize revenue, 250 persons should go on the trip.