The applicable formula is A = P(r/12)/(1 -(1+r/12)^(-12n)) where P is the principal amount, r is the annual interest rate (compounded monthly), and n is the number of years.
Using the formula, we find A = 84,400*(0.04884/12)/(1 -(1+0.04884/12)^(-12*15)) = 84,400*0.00407/(1 -1.00407^-180) = 343.508/0.518627 ≈ 662.34
The monthly payment on a mortgage of $84,400 for 15 years at 4.884% will be $662.34
