part B please~ thank you!

prof posted the answer: Rf = -2.65% ; Rm= 7.1167% but i don't know why, I got a different result

Eric Huang currently has holdings in the following three stocks A, B, C Expected Standard B returns deviation A A 14.93% 18% 1.8 1 B 12% 15% 1.5 0.6 10.2% 11% 1.1 0.8 Correlations B 0.6 0.8 1.0 -0.9 -0.9 1.0 a. What would be the expected return, standard deviation, and B for the following portfolios: Portfolio M $60,000 in A and $40,000 in B? Portfolio N $50,000 in B and $50,000 in C? b. From your results in (a), if the CAPM holds, what is the risk-free rate and the expected return of the market? c. Which one is the better portfolio and why