I assume you mean you want to solve for the mortgage payment

B = mortgage value = 100,000
i = interest rate = Rate/12 (normal mortgages are compounded monthly) = (0.095)/12 = 0.0079
n = number of months = 20 * 12 = 240

Payment = (B * i) / (1-(1+i)^-n)
Payment = (100,000 * 0.0079) / (1 - (1+0.0079)^-240)
Payment = 932.13

well, this is pen, paper and calculator but I think it is what you want.