3- please explain

Determine the tax-free amount of the monthly payment in each of the following instances.

1. Person A is age 66 and purchased an annuity for $91,000. The annuity pays $2,000 per month for life. (Round exclusion percentage computation to one decimal place.)
2. Person B is 75 and purchased an annuity for $89,000. The annuity pays $1,400 per month for life. (Round exclusion percentage computation to one decimal place. Round your final answer to 2 decimal places.)
3. Person C is 68 and purchased an annuity for $49,000 that pays a monthly payment of $1,000 for 12 years. (Round exclusion percentage computation to one decimal place. Round your final answer to 2 decimal places.)

What's the correct answer please provide examples?

a.	Tax free portion of payments	$255selected answer incorrect
b.	Tax free portion of payments	$479.75selected answer incorrect
c.	Tax free portion of payments	$340.28selected answer correct