please help me with these 2 exercises!!!

Consider the following information a. What is the expected return on an equally w eighted portfolio of these three stocks? b. What is the variance of a portfolio invested 20 percent each in A and B, and 60 percent in C? Systematic versus Unsystematic Risk Conside r the following information about Stocks I and II: The market risk premium is 7.5 percent, and t he risk-free rate is 4 percent. Which stock has the most systematic risk? Which one has the most unsystematic risk? Which stock is "riskier"? Explain