Problem $6\mathrm{.}39($L$06\mathrm{.}5)$

David is a college professor who does some consulting work on the side. He uses $25\%$ of his home exclusively for the consulting

practice. He is single and $63$ years old. HIs AGI $($without consideration of consulting income$)$ is $$45,000.$ Other Information follows:

Required:

Calculate David's AGI.