eBook Problem Walk-Through Susan and Stan Britton are a married couple who file a joint income tax return, where the tax rates are based on the tax table 3.5. Assume that their taxable income this year was $275,000. Do not round intermediate calculation a. What is their federal tax liability? Round your answer to the nearest dollar $ b. What is their marginal tax rate? Round your answer to the nearest whole number % c. What is their average tax rate? Round your answer to two decimal places. %