Ron used to work as a marketing executive for $80 000 per year but quit in order to start his lawn care business. To buy the necessary equipment, he withdrew $40 000 from his savings which paid 3 percent interest per year and borrowed $60 000 from the bank, in which he also pays 3 percent interest per year. Last year he paid $50 000 for materials and had revenue of $120 000. What is the implict cost for last year of operation?