Frankie’s car broke down. The repair costs are $400. Because he does not have any money saved, he will have to get a “payday loan” for the car repair. He researched 7- day payday loans and found that he will owe $9.50 for every $100 he borrows, plus the money he borrows. How much will Frankie have to pay back, if he takes the 7- day payday loan?