b) Professors Annuity Corp. offers a lifetime annuity to retiring professors. The interest rate is 6 percent, monthly compounding. If the professors remaining life expectancy is 20 years, for a payment of $80,000 at age 65, what monthly annuity payment can the firm offer to the retiring professor?

Here is the answer she gave us... We need to calculate the monthly rate rm = APR m = 6% 12 = 0.5%. So the monthly payment is 80, 000 = P V = C [1/0.5% 1 / 0.5% (1+0.5%)^1220] Therefore C = $573.14

My math is not good how do you calculate using only pen, paper, and calculator to get 573.14 for last part of question