Help me with this please--- no excel--- I want to understand how with formulas and my calculator......I already know the answer to this I just need someone to explain the steps please and thank you!

Sommers Industries has a bond outstanding with a 20-year maturity, an 8% coupon paid semiannually, and a $1,000 par value. The bond has a 7% nominal annual yield to maturity, but it can be called in 5 years at a price of $1,080. What is the bonds yield to call?