A married couple from California is in the $35\%$ Federal tax bracket and the $11\%$ California tax bracket. They are considering a $6\%$ Arizona municipal bond $($Federal tax$-$free$),$ a $5\frac{1}{2}\%$ California bond $($double tax$-$free$)$ or an $8\%$ corporate bond $($fully$-$taxable$).$ Which bond offers the highest after$-$tax interest rate?

A married couple from California is in the $35\%$ Federal tax bracket and the $11\%$ California tax bracket. They are considering a $5\%$ Arizona municipal bond $($Federal tax$-$free$),$ a $4\frac{1}{2}\%$ California bond $($double tax$-$free$)$ or a $7\%$ corporate bond $($fully$-$taxable$).$ Which bond offers the highest after$-$tax interest rate?