Define marginal cost and calculate brazils marginal cost of

Question

Question: Define marginal cost and calculate Brazil's marginal cost of producing a tonne of food when the quantity produced is 2.5 tonnes per day.

     Ethanol                                   Food crops
(barrels per day)                        (tonnes per day)

       70                   and                      0

       64                   and                      1

       54                   and                      2

       40                   and                      3

       22                   and                      4

        0                    and                      5