A $30-$year maturity, $8\%$ coupon bond paying coupons semiannually is callable in $5$ years at a call price of $$1,100.$ The bond currently sells at a yield to maturity of $7\%.$

a$.$ What is the yield to call?

b$.$ What is the yield to call if the call price is $$1,050?$

c$.$ What is the yield to call if the call price is $$1,100$ but the bond is callable in $2$ years instead of $5?($PLEASE DO NOT JUST SHOW EXCEL! SHOW THE CALCULATIONS$)$