The premium of a call option with a strike price of $50 is equal to $5.5 and the premium of a call option with a strike price of $55 is equal to $4. The premium of a put option with a strike price of $50 is equal to $3.5. The risk-free rate of interest is 9%. In the absence of arbitrage opportunities, what should be the premium of a put option with a strike price of $55? All these options have a time to maturity of 6 months. (You are not allowed to use the put-call parity to solve this problem)