You are an investor in common stock, and you currently hold a well-diversified portfolio that has an expected return of 10%, a beta of 1.2, and a total value of $12,000. You plan to increase your portfolio by buying 1,000 shares of X at $15 a share. X has an expected return of 15% with a beta of 1.8. What will be the expected return of your portfolio after you purchase the new stock?