I need help with this.

3. Consider the risk-return relationship for a portfolio that combines a risk-free asset and a risky asset, assuming that rf = .05 , E(RA) = .15 , and 0A = .2. A. What is the reward per unit risk? B. What is the equation for the portfolio's risk-return relationship? Please graph it. C. If an investor puts 25 percent of her portfolio wealth into the risk-free asset and 75 percent into the risky asset, what will be her portfolio's expected return and risk? Please show on your graph