7. A train carries 2 000 passengers daily. The cost to ride the train is $7.00 per person. Studies show that 40 fewer people would ride the train for each $0.10 increase in the fare, and 40 more people would ride the train for each $0.10 decrease. If the capacity of the train is 2 600 passengers, and carrying fewer than 1 600 passenger means costs exceed revenue, what fare should the railway charge to get the largest possible revenue