please show how to solve using a formula without calculator functions or excel. I need to know hot to solve it without any props

3. Boulder Furniture has bonds outstanding that mature in 13 years, have a 6 percent coupon, and pay interest semi-annually. These bonds have a face value of $1,000 and a current market price of $1,040. What is the company's after-tax cost of debt if its tax rate is 32 percent? a