In a survey of a TriDelt chapter with 50 members, 21 were taking mathematics, 32 were taking English, and 7 were taking both. How many were not taking either of these subjects?

Answer 1

N(M or E) = N(M) + N(E) - N( M and E) + other
50 = 21 + 32 - 7 + other
other = 4

or

If you know Venn diagrams, this is a real easy one to set up