Please show formulas used and work, thanks.

I. You own a portfolio of two stocks. Red River Inc. has an expected return of 9% and a standard deviation of 15% while Boston Harbor Co. has an expected return of 15% with a standard deviation of 19%. A) (4 points) What percent of your portfolio must you invest in each stock if you wanted to earn a 12.4% return on the portfolio? (Hint: consider wi + w2-10) B) (7 points) If the correlation coefficient is 0.3, what is the standard deviation of this portfolio? Is risk reduced at these weights relative to the risk of the individual assets? Why