What would be the marginal and average tax rates for a married couple with taxable income of $90,000? For an unmarried taxpayer with the same income? Use Table 3.7. (Do not round intermediate calculations. Enter the marginal tax rate as a percent rounded to 1 decimal place. Enter the average tax rate as a percent rounded to 1 decimal place.) a. What would be the marginal tax rate for a married couple with income of $90,000? b. What would be the average tax rate for a married couple with income of $90,000? c. What would be the marginal tax rate for an unmarried taxpayer with income of $90,000?