In: Advanced Math
Pmt = Periodic payment = $1800
i = interest rate per period = 6.1% = 6.1/100 = 0.061
and compounded monthly so I = 0.061/2 = 0.0050833
n = Number of payments = 30 years = 30 x12 = 360
we can use below formula
PV = Pmt x [(1 - 1 / (1 + i)n)] / i
PV = 1800 x [(1 - 1 / (1 + 0.0050833)360)] / (0.0050833)
PV = 1800 X [(1-1/(1.0050833)360)]/( 0.0050833)
PV = 1800 X [1-1/(6.20498)]/( 0.0050833)
PV = 1800 X [1-0.16116]/( 0.0050833)
PV = 1800 X [0.83884]/( 0.0050833)
PV = 1800 X 165.018787
PV = 297033.816 ~ 297034
So the present value of annuity is $297034
Amortized amount P = $170000
rate r = 3% = 3/100 = 0.03
and compounded monthly so r = 0.03/12 = 0.0025
And number of payments = 25 x 12 = 300
PMT = [ p x r x (1+r)t ] / [(1+r)t-1]
PMT = [170000 x 0.0025x (1+0.0025)300 ] / [(1+0.0025)300-1]
PMT = [425 x 2.11501] / [2.11501 - 1]
PMT = [898.879] / [1.11501]
PMT = 806.1625 ~ 806
So MONTHLY PAYMENT amount is $806