18. Porter Co. began its business last year and issued 10,000 shares of common stock at $3 per share. The par value of the stock is $1 per share. During January of the current year, Porter bought back 500 shares at $6 per share, which were reported by Porter as treasury stock. The treasury stock shares were reissued later in the current year at $10 per share. Porter used the cost method to account for its equity transactions. What amount should Porter report as paid-in capital related to its treasury stock transactions on its balance sheet for the current year? a. $1,500 b. $2,000 c. $4,500 d. $20,000