Declan and Olivia are married and will file a joint tax return. Olivia has a sole proprietorship (not a "specified services" business) that generates qualified business income of $300,000. The proprietorship pays W-2 wages of $40,000 and holds property with an unadjusted basis of $10,000. Declan is employed by a local school district. Their taxable income before the QBI deduction is $389,800 (this is also their modified taxable income). a. Determine Declan and Olivia's QBI deduction, taxable income, and tax liability for 2021. b. After providing you the original information in the problem, Declan finds out that he will be receiving a $6,000 bonus in December 2021 (increasing their taxable income before the QBI deduction by this amount). Redetermine Declan and Olivia's QBI deduction, taxable income, and tax liability for 2021. c. What is the marginal tax rate on Declan's bonus?