can you answer this question for me please and using excel to answer it ?

Assume that you manage a risky portfolio with an expected rate of return of 15% and a standard deviation of 37%. The T-bill rate is 5% A client prefers to invest in your portfolio a proportion (y) that maximizes the expected return on the overall portfolio subject to the constraint that the overall portfolio's standard deviation will not exceed 25%. Required: a. What is the investment proportion, y ? (Do not round intermediate calculations. Round your answer to 2 decimal places.) 36 b. What is the expected rate of return on the overall portfolio? (Do not round intermediate calculations. Round your answer to 2 decimal places.) 36