Please help me solve questions 4 through 8. I am having trouble finding the Marginal Cost.

Delta Airlines has frequent (every hour or every two hours) flights between key metropolises in the Northeast - they call these flights the "Delta Shuttle" service.At the time of writing this problem set, the Shuttle service is offered between New York and Boston (LGA-BOS), DC (LGA-DCA), and Chicago (LGA-ORD).

In the late 90s, Delta offered special student pricing on the Boston route, perhaps due to the fact that Boston is a college city (Boston University, Boston College, MIT, Harvard, etc.), but then discontinued the program in early 2000.Now Delta is re-considering decisions on their shuttle route.The MD-88 plane has 148 seats and the Embraer 175 has 76 seats.Please see the accompanying Excel with the pricing data.

Delta Airline Costs

Delta Airlines Aircraft Operating Costs Cost Per Block Hour (Block Hour is the time from gate departure to gate arrival) E-175 $4,457 MD-88 $6,128 Pilots $592 Pilots $686 Salaries and Wages $363 Salaries and Wages $458 Pilot Training $6 Pilot Training $8 Benefits and Payroll Taxes $175 Benefits and Payroll Taxes $172 Per Diem/ Personnel $48 Per Diem/ Personnel $47 Purchased Goods $2,263 Purchased Goods $3,463 Fuel/Oil $2,250 Fuel/Oil $3,450 Insurance $13 Insurance $13 Other (inc. Tax) SO Other (inc. Tax) SO Maintenance $1,267 Maintenance $1,387 Labor $65 Labor $56 Materials $168 Materials $163 Third Party $270 Third Party $337 Total Direct $485 Total Direct $556 Burden $279 Burden $274 Aircraft Ownership $104 Aircraft Ownership $203 Rentals $68 Rentals $123 Depreciation and Amortization $36 Depreciation and Amortization $79 Other $230 Other $391