Every morning when Tim wakes up, he groggily searches around his sock drawer and picks two socks randomly. If he has 10 gray-bottomed socks and 8 white-bottomed socks in his drawer, what is the probability that he picks a matching pair?
\(\dfrac{10}{18}\dfrac{9}{17} + \dfrac{8}{18}\dfrac{7}{17} = \dfrac{73}{153}\)
+885 
