If 9 play none, of the 29 students, 29-9 =20 play at least one. If 14 play basketball, then 20-14 = 6 play only baseball. Since 8 play baseball, there must be 8-6 = 2 who play both baseball and basketball.
Choosing at random, the probability is 2/29 that a student will be chosen who plays both sports.
