Can somebody explain in great detail how to find a and b? ?

Fixed rate mortgage offer: purchase price: $170,000 down payment ($34k): 20% term: 30 years interest rate: 4.25% property tax (yearly): $1,500 homeowner’s insurance (yearly): $1,000 use this example from a fixed-rate mortgage calculator to you answer the questions. keep the page open after you complete this question. according to the calculator, the monthly payment demarco and tanya should anticipate paying for principal and interest is $208. $877. $669. $1,200.