For $2023,$ determine the maximum contribution that can $be$ made $to$ a Keogh plan $in$ each $of$ the following cases. $In$ all

instances, the individual $is$ self$-$employed, and the self$-$employment tax reduction has already been taken.

Required:

$a.$ Self$-$employment income $of$ $$71,400.$

$b.$ Self$-$employment income $of$ $$71,400$ and wage income $of$ $$30,400.$

$c.$ Self$-$employment income $of$ $$115,000.$

$d.$ Self$-$employment income $of$ $$355,400.$