Julio buys a koi fishpond (and fish to put in it) for his wife on their anniversary. He pays $8000 for the pond and fish with $2000 down. The dealer charges add-on interest of 3.5% per year, and Julio agrees to pay the loan with 36 equal monthly payments. Use this information to answer the following questions: 1) Find the total amount of interest he will pay. 2) Find the monthly payment. 3) Find the APR value (to the nearest half percent). 4) Find (a) the unearned interest and (b) the payoff amount if he repays the loan in full with 12 months remaining. Use the most accurate method available.