Please I need the anwsers with all steps clearly please

a a. A stock has a beta of.9 and an expected return of 9 percent. A risk-free asse currently earns 4 percent What is the expected return on a po tfolio that is equally invested in the two assets? b. If a portfolio of the two assets has a beta of 0.5, what are the portfolio weights? If a portfolio of the two assets has an expected return of 8 percent, what is its beta? c