4. If your total taxable income for one year is d dollars, let I(d)be the federal income tax that you owe. For 1993, the value of 1 (d ) was given (approximately) by: 0.15d if 0 s d 3 20,000 1(d) = 3000 + 0.28(d 20,000) if 20,000 49,000 a. Suppose the IRS suddenly declared that your new tax obligation was [(61 )+ 200. Explain how this changes your tax obligation. b. Suppose instead the IRS suddenly declared that your new tax obligation was I (d +1000).Explain how this changes your tax obligation. c. If your taxable income was $15,000, would you prefer the 1(d )+ 200 or the [(41 + 1000) system? Explain your reasoning