A survey of 100 students in an institution shows that 80 students speak Hausa and 20 students speak Igbo, while only 9 students speak both language. How many students speak neither Hausa nor Igbo?

A.
0 
B.
9 
C.
11 
D.
20
Correct Answer: Option B
Explanation
Let the number of students that speak Hausa and Igbo be represented by H and I respectively.
n(H only) = 80 – 9 = 71.
n(I only) = 20 – 9 = 11.
n(neither H nor I) = 100 – (71 + 9 + 11)
= 100 – 91 = 9 students.