Krystyna, a single individual, invested $20,000 in corporate bonds with a stated interest rate of 5 percent and another $20,000 in tax-exempt municipal bonds issued for governmental activities with a stated interest rate of 4.75 percent. Calculate her after-tax cash flow from each investment if:
a. her marginal tax rate is 15 percent.
b. her marginal tax rate is 33 percent and her modified adjusted gross income is $430,000.