There are five cards, two red and three black. You draw two cards, without replacement. What is the probability that both have the same color?
P(two red) = (2/5)(1/4) = 2/20 = 1/10
P(two black) = (3/5)(2/4) = 6/20 = 3/10
Add the probabilities = 4/10 = 2 / 5