Suppose that 10 cards, of which five are red and five are green, are placed at random

Question:

Suppose that 10 cards, of which five are red and five are green, are placed at random in 10 envelopes, of which five are red and five are green. Determine the probability that exactly x envelopes will contain a card with a matching color (x = 0, 1, . . . , 10).