Mrs$.$ Yue, a resident of Virginia, paid $50,000$ for a bond issued by Pennsylvania that paid $3,400$ interest this year. Her marginal state income tax rate is $6$ percent. Under Virginia law, interest on debt obligations issued by another state is taxable. Mrs$.$ Yue can deduct her state income tax on her From $1040,$ and her marginal federal income tax rate is $24$ percent. Crateompute her after$-$t; herax rate of return on the bond.

I believe the answer is $6\mathrm{.}49\%$ just need help with how they found that. $.$