Please help me understand how the answer to this question is B using formulas or a financial calculator if applicable.

12. Assume that you have $330,000 invested in a stock that is returning 11.50%, $170,000 invested in a stock that is returning 22.75%, and $470,000 invested in a stock that is returning 10.25%. The risk free rate is 2.1% and inflation is 5%. What is the expected return of your portfolio? A) 15.6%. B) 12.9% C) 18.3%. D) 14.8% Answer: B