$1.$ Single Taxpayer, who is an employee of a law firm, in the current year has $$100,000$ of adjusted gross income, and the following allowable itemized deductions: $$6,000$ in interest, $$6,500$ in state income taxes, $$1,500$ in unreimbursed employee travel expenses, $$200$ in tax preparation fees, and $$300$ bar association dues. For simplicity, assume that there are no inflation adjustments.

$($a$)$ What is Taxpayer's taxable income for the current year?

$($b$)$ What difference in result in $($a$),$ above, if Taxpayer's $65$th birthday is January $1$ of the succeeding year. See Reg. $1\mathrm{.}151-1($c$)(2).$

$($c$)$ What difference in result under the facts of $($a$),$ above, if Taxpayer is a married couple filing a joint return?

$($d$)$ What difference in result under the facts of $($c$),$ above, if Taxpayers' deductible interest is $$10,000,$ the state income taxes are $$12,000,$ and the Taxpayers have a $$5,000$ charitable contribution.