PLEASE HELP and provide step by step calculations so I can understand where I am going wrong with mine....

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:

1. Self-employment income of $57,000.
2. Self-employment income of $57,000 and wage income of $30,000.
3. Self-employment income of $125,000.
4. Self-employment income of $295,000.

Amount

a.Maximum Keogh plan contribution $____$11,400______

b.Maximum Keogh plan contribution $____$11,400_____

c.Maximum Keogh plan contribution $________________

d.Maximum Keogh plan contribution $______$57,000________