Campbell, a single taxpayer, earns $407,500 in taxable income and $2,600 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 $16,500 of taxable income, what is her marginal tax rate on this income? b. What is her marginal rate if, instead, she had $16,500 of additional deductions? (For all requirements, do not round intermediate calculations. Round percentage answers to whole percent.) a. Marginal tax rate b. Marginal tax rate % %