Calculate the after-tax return of a(n) 7.05 percent, 20-year, A-rated corporate bond for an investor in the 10 percent marginal tax bracket. Compare this yield to a(n) 5.14 percent, 20-year, A-rated, tax-exempt municipal bond, and explain which alternative is better. Repeat the calculations and comparison for an investor in the 35 percent marginal tax bracket.