P(Y =1) = P(X=1,Y=1) + P(X=2,Y=1) = 0.1 + 0.2 =0.3P(X =2) = P(X=2,Y=1) + P(X=2,Y=2) + P(X=2,Y=3) = 0.2 + 0.1+ 0.2 = 0.5
