Use the formula of the present value of an annuity ordinary which is
Pv=pmt [(1-(1+r/k)^(-kn))÷(r/k)]
Pv present value 85000
PMT monthly payment?
R interest rate 0.05
K compounded monthly 12
N time 10 years
Solve the formula for PMT
PMT=Pv÷[(1-(1+r/k)^(-kn))÷(r/k)]
PMT=85,000÷((1−(1+0.05÷12)^(
−12×10))÷(0.05÷12))
=901.55 round to the nearest tenth to get 900
Hope it helps!