Your formula is written wrong and therefore you will get a wrong answer. That is why the answer of "Guest 1" is wrong. It looks to me that you are trying to calculate a monthly payment on a loan of $28,000 @ 7.45% compounded monthly for a period of 3 years or 3 x 12 =36 months.
The proper formula to use is this:
PMT=PV. R.{[1 + R]^N / [1 + R]^N - 1}
PMT = 28,000 x 0.0745/12 x {[1 + 0.0745/12]^3*12 / [1 + 0.0745/12]^3*12 - 1}
PMT =173.833... x {[ 1.249582] / [ 0.249582]}
PMT =173.833....x 5.00669957
PMT = $870.33, which the correct monthly payment on this loan.
