In a pack of 52 cards, there are 4 king cards and 4 queen cards

Let A denote the event that the card drawn is queen and B denote the event that card drawn is king.

Then,

P(A) = 4/52 and P(B) = 4/52

As a card cannot be both king and queen in the same time, so P(A and B) = 0

Using formula, P(A or B) = P(A) + P(B) – P(A and B)

P(A or B) = 4/52 + 4/52 – 0

= 2/13

Probability of a card drawn is king or queen = P(A or B) = 2/13