Need help with the calculation of mean and variance of the portfolio.

exxonpr oilpr S.P500 Mean 30.265 20.372 446.63 Variance 247.03 22.94 64120.61 Standard Deviation 15.71 4.789 253.22 Skewness 1.150 0.843 1.2859 Kurtosis 3.82 3.61 3.95 Min 9.16 11.13 150.55 Max 75.63 37.09 1229.23 Calculate the mean and the variance of a portfolio that you may build to your choice, with either 2 or the 3 of stocks for prices are given (with share 50% each if use 2 stocks, and 35%+35%+30% if you use 3 stocks); the choice is yours