25% because if you have 4 cards which would equal 100% and you are dealt 2 you have a 25% chance of getting any of the 4. (25x4=100)
But, if you are talking about probability of color it would be 50% because if you have 2 red cards and the total deck is 4 cards, then that is already half of the deck. And if you have 2 black cards then that makes up the other half. but if you are talking individually like Red 1 and Red 2 and Black 1 and Black 2 separating them would create a 25% probability. So, x= 25% (infivudually) or 50% (by color)