For example, suppose that a four year 5% annual coupon payment bond is priced at 105 per 100 of par value. The yeild to maturity is the solution for the rate, r in this equation:

105 = (5/(1+r)^1) + (5/(1+r)^2)+(5/(1+r)^3) + (105/(1+r)^4)

Need to know how to solve for R analytically step by step please. Thank you.