a. Calculate the tax liability, after-tax earnings, and average tax rates for the following levels of corporate earnings before taxes: $ 11,200 ; $ 79,200 ; $ 303,000 ; $ 499,000 ; $ 1.2 million; $ 9.7 million; and $ 19.9 million. b. Plot the average tax rates (measured on the y axis) against the pretax income levels (measured on the x axis). What generalization can be made concerning the relationship between these variables?

$0_to $50,000 $0 + (15% amount_over $0) 50,000_to 75,000 7,500 + (25% amount_over 50,000) 75,000_to 100,000 13,750 + (34% amount_over 75,000) 100,000_to 335,000 22,250 + (39% amount_over 100,000) 335,000_to 10,000,000 113,900 + (34% amount_over 335,000) 10,000,000_to 15,000,000 3,400,000 + (35% amount_over 10,000,000) 15,000,000_to 18,333,333 5,150,000 + (38% amount_over 15,000,000) Over_18,333,333 * 6,416,667 + (35% amount_over 18,333,333)