In calculating the simple interest earned by an investment, the equation P = P₀ + P₀ rt is used, where P is the value after an initial principal P₀ is invested for t years at interest rate r. Solve for r, and then evaluate r for P = $7625, P₀ = $6250,  and t = 4.000years. Write a paragraph or two explaining 

(a) Your method for solving for r

(b) The calculator steps used to evaluate r, noting the use of parentheses.