Can i get a,b and c solved step by step please (not excel)

7. A 30-year maturity, 12% coupon bond paying coupons semiannually is callable in ten years at a call price of $1,100. The bond currently sells at a yield to maturity of 8%. (15 points) a. What is the yield to call? b. What is the yield to call if the call price is only $1,050? c. What is the yield to call if the call price is $1,100 but the bond can be called in five years instead of ten years