The number of hardware failures X and the number of software

The number of hardware failures, X, and the number of software failures, Y, on any day in a small computer lab have the joint distribution P(x,y), where P(0,0) = 0.6, P(0,1) = 0.1, P(1,0) = 0.1, P(1,1) = 0.2. Based on this information:

Compute E(X +Y), i.e., the expected total number of failures during 1 day.