Calculating the Variance of Random Variables

Consider two random variablesX and Y. Suppose that the varianceof X is 10, that this of Y is 40, and that the covariance of X and Y is 15. What is the variance of the random variable2X+Y? (Hint: Look at slide 45 of set 3 of lecture notes, or page 242 of text book)

80
90
110
140

This solution provides calculations of variance for random variables.