Campbell, a single taxpayer, earns $$400,000$ in taxable income and $$2,000$ in interest from an investment in State of New York bonds. $($Use the U$.$S$.$ tax rate schedule.$)$

Required:

a$.$ If Campbell earns an additional $$15,000$ of taxable income, what is her marginal tax rate on this income?

b$.$ What is her marginal rate if$,$ instead, she had $$15,000$ of additional deductions?

Note: For all requirements, do not round intermediate calculations. Round percentage answers to whole percent.

$\backslash$table$[[$a$.$ Marginal tax rate,$4\%$