Use a formula to find the monthly payment on a home mortgage of $84,400 at 4.884% interest for 15 years.

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