Required: 15 You buy a share of stock, write a one-year call option with X= $13, and buy a one-year put option with X= $13. Your net outlay to establish the entire portfolio is $12.50. What is the payoff of your portfolio? What must be the risk-free interest rate? The stock pays no dividends. (Do not round intermediate calculations. Round "risk-free rate" to 2 decimal places.) Payoff Risk-free rate %