6. A bond is selling for $1,248.49, has a 6.6% annual coupon rate, 20 years left until maturity, and a $1,000 par value. It has a call provision allowing the issuing firm to call the firm back in 7 years. To do so, they must pay a 15% premium to par value. What is the bond's Yield to Call? Do it in excle with formula