(Solving for r in an annuity) Your folks just called and would like some advice from you. An insurance agent just called them and offered them the opportunity to purchase an annuity for $21,096.45 that will pay them $3,500 per year for 10 years, but they don't have the slightest idea what return they will be making on their investment of $21,096.45. What rate of return will they be earning? The annual rate of return they will be earning is %. (Round to two decimal places.)