I am taking intro to SEM class. I need help regarding the Cov and Var matrix which I try hard to understand through this class.

X, Y, Z, and W are random variables with the same variance of 1.5 then Covariances: Cov(X,Y) = .5; Cov(Z,W) = .6 = Cov(X,W), Cov(Y,Z) = .3. Then I have to find the following

cov(s) and var(s)

1) Var(X+2Y),

2) Var(3Z+4W),

3) Cov(2X+3Z, 5Y+3W)

4) Cov(3Y+2W, 5X+1.5Z)

Thank you in advance