Tuco Furniture Outlet is issuing 15-year, 7 percent callable bonds. These bonds are callable in 4 years with a call premium of $45. The bonds are being issued at par and pay interest semi-annually. What is the yield to call?

Can you explain on how to solve this problem using a graphic calculator step by step so I can learn it please I dont want the answer. I want to know how to solve it. Thank you.