In a small high school with 20 seniors, 8 of the seniors
are in soccer, 9 of the seniors are in band, and 5 of the
seniors are in both. How many seniors are in neither
soccer nor band?
The Venn diagram:
We start with 5 in the middle (both soccer and band). Since we know that 8 players are in soccer, we know that there must be 3 that play only soccer.
Since there are 9 total band members, there must be 4 that are only in band.
The number of students should add up to 20.
neither band or soccer+3+5+4=20
neither band or soccer+12=20
neither band or soccer=8