My answers were wrong i can't figure out the formula

Chuck, a single taxpayer, earns $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 rate on this income? b. What is his marginal rate if, instead, he had $40,000 of additional deductions? (For all requirements, do not round intermediate calculations. Round percentage answers to 2 decimal places.) Marginal tax rate Marginal tax rate 26.001% 24.53% b. 2020 Tax Rate Schedules Individuals Schedule X-Single If taxable income is over:But not over: $ 0 $ 9,875 $ 9,875 $ 40,125 $ 40,125 $ 85,525 $ 85,525 $163,300 $163,300 $207,350 $207,350 $518,400 $518,400 The tax is: 10% of taxable income $987.50 plus 12% of the excess over $9,875 $4,617.50 plus 22% of the excess over $40,125 $14,605.50 plus 24% of the excess over $85,525 $33,271.50 plus 32% of the excess over $163,300 $47,367.50 plus 35% of the excess over $207,350 $156,235 plus 37% of the excess over $518,400