Problem 1-37 (LO 1-3) Campbell, a single taxpayer, earns $260,000 in taxable income and $4,400 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 $18,000 of taxable income, what is her marginal tax rate on this income? b. What is her marginal rate if, instead, she had $18,000 of additional deductions? (For all requirements, do not round intermediate calculations.) a. b. Marginal tax rate Marginal tax rate