Chuck, a single taxpayer, earns $$79,600$ in taxable income and $$15,600$ in interest from an investment in City of Heflin bonds. $($Use the U$.$S$.$ tax rate schedule.$)$

Required:

A$.$ If Chuck earns an additional $$40,000$ of taxable income, what is his marginal tax rate on this income?

B$.$ What is his marginal rate if$,$ instead, he had $$40,000$ of additional deductions?