finance..HELP...i need the steps shown ....i dont understand how to get the answer?

[txfinest84]

Realized rates of return Stocks A and B have the following historical returns:
Year Stock A’s Returns, rA Stock B’s Returns, rB
2001 (18.00%) (14.50%)
2002 33.00 21.80
2003 15.00 30.50
2004 (0.50) (7.60)
2005 27.00 26.30
a. Calculate the average rate of return for each stock during the period 2001 through 2005.
b. Assume that someone held a portfolio consisting of 50 percent of Stock A and
50 percent of Stock B. What would the realized rate of return on the portfolio have
been in each year? What would the average return on the portfolio have been
during this period?
c. Calculate the standard deviation of returns for each stock and for the portfolio.
d. Calculate the coefficient of variation for each stock and for the portfolio.
e. Assuming you are a risk-averse investor, would you prefer to hold Stock A, Stock B,
or the portfolio? Why?