Please, solve the following tasks

and show their solutions written with explanation of all steps and calculations.

/Opportunity cost/

After college graduation, Maria, who lives separate from her parents, entered the one year master program in public university. College graduate in this city can work either as an accountant with a salary of 4 800 UAH per year or as a seller with a salary of 3000 UAH per year. What is the opportunity cost of studying at master program if Maria should pay for the usage of university resources 500 UAH a year, and the cost of rent and food is 2800 UAH a year?