William is a single writer $($age $35)$ who recently decided that he needs to save more for retirement. His $2023$ AGI before the IRA contribution deduction is $$80,000($all earned income$).$

Note: Leave no answers blank. Enter zero if applicable.

b$.$ If he does participate in an employer$-$sponsored plan, what is the maximum deductible IRA contribution William can make in $2023?$c$.$ Assume he does participate in an employer$-$sponsored plan, and his AGI before the IRA contribution deduction is $$89,000.$ What is the maximum deductible IRA contribution William can make in $2023?$