In a fraternity with 38 ​members, 18 take​ mathematics, 5 take both mathematics and chemistry​, and 8 take neither....

Question

In a fraternity with 38 members, 18 take​ mathematics, 5 take both mathematics and chemistry​, and 8 take neither mathematics nor chemistry. How many take chemistry but not​ mathematics?

Answer 1

1. Total = 38 = A + B + C + D
2. 18 = B + C
3. 5 = C
4. 8 = A

Work from the end to the beginning:

A = 8

C = 5

B = 13 [from clues 3 and 2]

D = 12 [use clue 1 and above info]

How many take chemistry but not​ mathematics? D = 12

Answer 2