Please answer with workings

You manage a risky portfolio with an expected rate of return of 18% and a standard deviation of 28%. The T-bill rate is 8%. Your risky portfolio includes the following investments in the given proportions: Suppose that your client decides to invest in your portfolio a proportion y of the total investment budget so that the overall portfolio will have an expected rate of return of 16%. a. What is the proportion y ? (Round your answer to the nearest whole number, but use the unrounded number in the following calculations for greater precision.) b. What are your client's investment proportions in your three stocks and the T-bill fund? (Do not round intermediate calculations. Round your answer to the nearest whole number, but use the unrounded number in the following calculations for greater precision.) c. What is the standard deviation of the rate of return on your client's portfolio? (Do not round intermediate calculations. Round your answer to 2 decimal places.)