In Cambridge, there are individuals from three different citizenships: Ethiopians, Brazilians, and Americans. Brazilians and Ethiopians only like to drink coffee from their own country, while for Americans a cup of coffee is the same regardless from its origin. All of them have the same level of income denoted by

Assignment:

Find the Utility function for each country (utility function for Americans, utility function for Ethiopians, utility function for Brazilians)

and

What is the magnitude (i.e. the absolute value) of the marginal rate of substitution for America, Ethiopia, and Brazil?