There are thirteen shirts in your closet, four blue, five green, and four red. You select one to wear. What is the probability that you pick a blue OR green shirt?
probability of picking blue = \(\frac{4}{13}\)
probability of picking green = \(\frac{5}{13}\)
probability of picking blue OR green = \(\frac{4 + 5}{13} = \boxed{\frac{9}{13}}\)