What is the probability of pulling a 5 or a heart from a deck of cards?

Well, if you include the jokers, you have 52 cards total. There are four suits, so that's four "5" cards in the deck, which gives you a 4 in 52 (or 2 in 21, simplified) probability. Each suit has 13 cards, so you have a 13 in 52 chance of pulling a card of any particular suit (13 is a Prime number, and can't be simplified).