Consider four 5-year European options with different strike price. The price of a 50-strike call option is higher than the price of a 60-strike call option by $7. The price of a 50-strike put option is lower than the price of a 60-strike put option by $1.9. All options are on the same stock and the stock pays dividends continuously at a rate proportional to its price. Determine the continuously compounded risk-free interest rate