please help

An investor purchases one municipal bond and one corporate bond that pay rates of return of 8% and 9.4%, respectively. If the investor is in the 15% tax bracket, his after-tax rates of return on the municipal and corporate bonds would be, respectively, 9.20% and 7.99% 8% and 7.99% 8% and 9.4% 6.80% and 9.4%