johnycute wrote:
This semester, each of the 90 students in a certain class took at least one course from A, B, and C. If 60 students took A, 40 students took B, 20 students took C, and 5 students took all the three, how many students took exactly two courses?
A. 15
B. 20
C. 25
D. 30
E. 35
Total = A + B + C - Two - 2*Three + Neither
90 = 60 + 40 + 20 - Two - 2*5 + 0
Two = 110 -90 = 20
IMO B
