Don Juan Perez runs a seafood restaurant on the central coast. His total income last year was $150,000. The rent was $48,000 per year. His labour costs were $42,000 and materials, food and other variable costs were $20,000. Don Juan Perez was going to work as a cookbook writer where he would have earned $40,000 per year, or as a chef de cuisine in another restaurant, where he would have earned $35,000. The economic utility of Don Juan Perez is:

Note: the answer is 0 (zero). Please clarify with calculations why this is the correct alternative.