A stock price is currently $20. It is known that at the end of one month that the stock price will either increase to 24 or decrease to 17. The risk-free interest rate is 12% per annum with continuous compounding. Using the no-arbitrage method (in which the portfolio consists of long shares and 1 short call), what is the value of for a European call option with strike price of $21?

(required precision 0.01 +/- 0.01)