Alpaca Airways flies between two airports within its own country. The plane used has capacity of 125 passengers. A one-way flight is priced at $80. The direct materials cost of the flight is $25, and the direct labour is $20. The flight has $4,000 fixed costs a) Calculate the marginal costs of a single flight b) Calculate the contribution per single flight c) Calculate the number of passengers required to cover the fixed costs d) What advice would you give to Alpaca Airways as a result of these calculations