Let A be the event of obtaining an even sum and B the event of obtaining a sum less than five, Then we have to find P(A∪B). Since A, B are not mutually exclusive,

we have P(A∪B) = P(A) + P(B) − P(A∩B)

$=\frac{18}{36}+\frac{6}{36}-\frac{4}{36}=\frac{5}{9}.$

since there are 18 ways to get an even sum and 6 ways to get a sum > 5,
viz. (1,3), (3,1), (2,2), (1,2), (2,1), (1,1) and 4 ways to get an even sum less than 5, namely, (1,3), (3,1), (2,2), (1,1).