Consider two portfolios A and B. At the expiration date, t, both portfolios have identical payoffs. Portfolio A consists of a put option and one share of stock. Portfolio B has a call option (with the same strike price and expiration date as the put option) and cash in the amount equal to the present value (PV) of the strike price discounted at the continuously compounded risk-free rate, which is Xe^- rRFt. At expiration, the stock price is P _t, and the value of this cash will equal the strike price, X. As defined in the Black Scholes model let N(d _i) stand for probability that a deviation less than d _i will occur in a standard normal distribution and N(d _1) and N(d _2) represent areas under a standard normal distribution function. Complete the equation for the value of a put option: Put option = Now consider the stock of Dada Enterprises (DE) traded at the price P = $20. A put option written on DE's stock has an exercise price of X = $25 and 18 months remaining until expiration. The risk-free rate is r _RF = 8%. A call option written on DE has the same exercise price and expiration date as the put option. If the ca option has a price of V _C = $6.50, then the price of the put c option is ______