Sam is going on a 1,200 mile road trip with 2 friends, who he will pick up
100 miles after he begins and drop off when there are 100 miles remaining.
The car consumes 2 gallons of gas for every 50 miles, and gas costs $2.50
per gallon. Same will pay for all of the gas when he is alone in the car, but
he and his friends will split the cost evenly when they are together. How
much will Sam pay for gas? *