One of the largest car dealers in the city advertises a 3-year-old car for sale as follows: Cash price $13,750, or a down payment of $1375 with 45 monthly payments of $361.23. Susan DeVaux bought the car and made a down payment of $2000. The dealer charged her the same interest rate used in his advertised offer. What is the monthly interest rate? How much will Susan pay each month for 45 months? What effective interest rate is being charged?