A card is drawn from a pack of 52 cards. What is the probability that either card is black or a king?

Number of cards in a pack of cards = 52

Number of black cards = 26

Number of king cards = 4 (2 Red, 2 Black)

Required, the probability that if a card is drawn either card is black or a king = 

$\frac{26}{52} + \frac{4}{52} = \frac{30}{52} = \frac{15}{26}$