You are in the $30\mathrm{.}0\%$ income tax bracket and looking to purchase one of two bonds:

Corporate Bond Yield to Maturity $=?$

Municipal $($Tax$-$exempt$)$ Bond Yield to Maturity $=4\mathrm{.}25\%$

What yield to maturity does the taxable corporate bond have to offer to be equivalent to the yield to maturity on the municipal bond?