The probability of picking a card from a deck

Question

You chose one card from a standard deck. What is the probability of picking a red card or a 4?

Answer 1

Pr(R or 4) = P(R) + P(4) - P(R&4) = 13/52 + 4/52 - 2/52 = 15/52=about 29%

if the standard deck is 52 cards

if the deck has 2 jokers, the answer is different