In a standard shuffled deck of 52 cards, half of the cards are black and half of the cards are red: (26 black cards, 26 red cards).
Since we are interested in pulling a black card first, the probability is 26/52.
Without replacing the card we have chosen, we are left with 51 total cards in the entire deck (25 black cards, 26 red cards).
Now that we want to pull a red card, we know that the probability will be 26/51.
Since we are interested in both events occurring simultaneously, we must multiply the probability of the first by the probability of the second, aka: (26/52) * (26/51)
The answer we are given is 0.2549