A: فوتبال و B: بسکتبال $ n(A \cup B) = 32 - 5 =27 \\ n(A) = 18 , n(B)=16 \\ n(A  \cup B) = n(A) + n(B) - n(A \cap B) \Rightarrow 27 = 18+16 - n(A \cap B) \Rightarrow n(A \cap B )=7 $ $ = n(A) - n(A \cap B) = 18 - 7 = 11 $ فقط فوتبال