The answer in the second pic I want know how he get this answer

4. A risky portfolio has an expected return of 17% and a standard deviation of27%. The treasury bill rate is 7%. An investor chooses to invest 70% of his money in the risky portfolio and the remainder in treasury bills. A. Find the expected return and standard deviation of the investor's portfolio. B. The risky portfolio consists of three assets as follows: stock weight 27% 33% 40% Find the investment proportions of stocks A, B, C, and treasury bills in the investor's portfolio. Find the slope of the combination line for the investor's portfolio. C