help me please

You are researching bond investments. A 20-year maturity, 8.8% coupon bond paying coupons semiannually is callable in seven years at a call price of $1,140. The bond currently sells at a yield to maturity of 7.8% (3.90% per half-year). a. What is the yield to call? (Do not round intermediate calculations. Round your answer to 2 decimal places.) Yield to call % b. What is the yield to call if the call price is only $1,090? (Do not round intermediate calculations. Round your answer to 2 decimal places.) Yield to call % c. What is the yield to call if the call price is $1,140 but the bond can be called in four years instead of seven years? (Do not round intermediate calculations. Round your answer to 2 decimal places.) Yield to call