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 $272,000. Do not round intermediate calculation. What is their federal tax liability? Round your answer to the nearest dollar. $ What is their marginal tax rate? Round your answer to the nearest whole number. % What is their average tax rate? Round your answer to two decimal places.