Chuck, a single taxpayer, earns $87,250 in taxable income and $32,500 in interest from an investment in City of Heflin bonds. (Use the U.S. tax rate schedule.)37950-91900 $5226.25 lus 25% of the excess over 37950. 91900-191650 $18713.75 plus 28% of the excess over 91900 (Do not round intermediate calculations. Round your answers to 2 decimal places.)

a. If Chuck earns an additional $63,750 of taxable income, what is his marginal tax rate on this income?

b. What is his marginal rate if, instead, he had $63,750 of additional deductions?