Answer
$\frac{5}{8}$
Work Step by Step
If their sum is even then we know that both numbers will have the same parity, thus we only need to calculate the probability of selecting an odd card in the first pull and the second pull as well.
The number of cases with an even sum of numbers $5\cdot4+4\cdot3=32$, out of these $5\cdot4=20$ have $2$ even cards. Thus the probability: $\frac{20}{32}=\frac{5}{8}$
