Chuck, a single taxpayer, earns $$78,400$ in taxable income and $$13,800$ 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?

Note: For all requirements, do not round intermediate calculations. Round percentage answers to $2$ decimal places.