Of the 12 full-time mathematics faculty at a high school, five drink coffee and eight do not enjoy teaching 8 a.m. classes. How many faculty both drink coffee AND enjoy teaching at 8 a.m.

2 answers

Use Venn digagrams
Intersect two circles, label one C the other T
let the intersection be x
then the part of C outside the intersection is 5-x
the part of T outside the intersection is 8-x

5-x + x + 8-x = 12
x = 1
i don't kno