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 $$64,200.$

b$.$ Self$-$employment income of $$64,200$ and wage income of $$38,000.$

c$.$ Self$-$employment income of $$185,000.$

d$.$ Self$-$employment income of $$331,000.$

$\backslash$table$[[,$Amount$],[$a$.$ Maximum Keogh plan contribution,$],[$b$.$ Maximum Keogh plan contribution,$],[$c$.$ Maximum Keogh plan contribution,$],[$d$.$ Maximum Keogh plan contribution,$]]$