The problem does not clearly give us the distance from Buffalo to Chicago, so let this be x (in mile) just so I can show you how the total cost is solved. The total cost is equal to the sum of the rental fee plus the cost of the additional fee per mile which is equal to 1.50x, and also of the cost of the gasoline which is equal to (x/16)(2.15). Thus, the final answer should be expressed as, total cost = 29.95 + 1.5x + 2.15x/16 When the distance is available, this should be easily substituted in the equation above.
