I cannot figure out how to do this problem, specially the formulas in excel

Monthly loan payments Personal Finance Problem Tim Smith is shopping for a used car. He has found one priced at $6,100. The salesman has told Tim that if he can come up with a down payment of $1,300, the dealer will finance the balance of the price at an annual rate of 15% over 4 years (48 months). (Hint: Use four decimal places for the monthly interest rate in all your calculations.) a. Assuming that Tim accepts the dealer's offer, what will his monthly (end-of-month) payment amount be? b. Use a financial calculator or spreadsheet to help you figure out what Tim's monthly payment would be if the dealer were willing to finance the balance of the car price at an annual rate of 9%? a. Tim's monthly (end-of-month) payment amount is $ 133.59. (Round to the nearest cent.) b. Tim's monthly payment, if the dealer were willing to finance the balance of the car price at an annual rate of 9%, would be $ 119.45. (Round to the nearest cent.)