William is a single writer (age 35) who recently decided that he needs to save more for retirement. His 2020 AGI before the IRA contribution deduction is $66,000 (all earned income).

a. If he does not participate in an employer-sponsored plan, what is the maximum deductible IRA contribution William can make in 2020?

b. If he does participate in an employer-sponsored plan, what is the maximum deductible IRA contribution William can make in 2020?

c. Assuming the same facts as in part (b), except William’s AGI before the IRA contribution deduction is $76,000. What is the maximum deductible IRA contribution William can make in 2020?