When a person’s income increases from $40,000 to $50,000 a year and tax payments increase from $3,000 to $6,000. What is the person’s marginal tax When a person’s income increases from $40,000 to $50,000 a year and tax payments increase from $3,000 to $6,000. What is the person’s marginal tax rate?When a person’s income increases from $40,000 to $50,000 a year and tax payments increase from...