In a group of 15 people; 7 can read French, 8 can read English while 3 of them can read neither of these two languages. Find the number of people who can read exactly one language.

Correct Answer: (B) 9

Out of 15 people, 3 read neither language, leaving $15 - 3 = 12$ people who read at least one language: $n(F$$\cup$ E) = 12. Using $n(F$$\cup$ E) = n(F) + n(E) - n(F $\cap$ E), we have $12 = 7 + 8 - n(F$$\cap$ E), so $n(F$$\cap$ E) = 3. The number of people reading exactly one language is $n(F$$\cup$ E) - n(F $\cap$ E) = 12 - 3 = 9.