i dont understand please explain in detail i thought the federal rate on the tax schedule was the answer

Chuck, a single taxpayer, eams $75,000 in taxable income and $10,000 in interest from an investment in City of Heflin bonds. (Use the U.S. tax rate schedule) Required: a. If Chuck earns an additional $40.000 of taxable income, what is his marginal tax rote on this income? b. What is his marginal rate if, instead, he had $40,000 of additional deductions? Note: For oll requirements, do not round intermediote calculotions. Round percentage answers to 2 decimal places. Individuals