Chuck, a single taxpayer, earns $168,000 in taxable income and $21,750 in interest from an investment in City of Heflin bonds. (Use the U.S. tax rate schedule.) (Do not round intermediate calculations. Round your answers to 2 decimal places.)

a.	If Chuck earns an additional $47,250 of taxable income, what is his marginal tax rate on this income?

b.	What is his marginal rate if, instead, he had $47,250 of additional deductions?