What is her after-tax yield (interest rate) on the bonds?

2.3 Theresa Davis is in the 40 percent personal tax bracket. She is considering investing in HCA (taxable) bond that carry a 12 percent interest rate.A. What is her after-tax yield (interest rate) on the bonds?B. Suppose Twin Cities Memorial Hospital has issued tax-exempt bonds that have an interest rate of 6 percent. With all else the same, should Theresa buy the HCA or the Twin Cities bonds?C. With all else the same, what interest rate on the tax-exempt Twin Cities bonds would make these bonds and the HCA bonds equally advantageous?