Please help!!!!

13. (2 points each) Consider the discrete random variables X and Y whose joint distribution is given in the following table, so P(X = -1 and Y = -1) = 1/4, P(X = -1 and Y = 1) = 1/2, etc. Y= -1 Y= 1 X= -1 4 1/2 X= 1 0 a). What is the marginal distribution of X? What is the marginal distribution of Y? b). Compute E(X) and E(Y). c). Compute Cov(X, Y)