Use PMT =[1(1+nr)nt](n) to determine the regular payment amount, rounded to the nearest dollar in terms of paying less in interest, which is more economical for a $160.000 mortgage: a 30 -year fixed-rate at 8.5% or a 20 -year fixed-rate at 8% ? How much is saved in interest? Use PMT =[1(1+nr)nt](n) to determine the regular payment amount, rounded to the nearest dollar in terms of paying less in interest, which is more economical for a $160.000 mortgage: a 30 -year fixed-rate at 8.5% or a 20 -year fixed-rate at 8% ? How much is saved in interest