We can make a Venn Diagram:
[baseball || both || football] neither
[ 37 || x || 26 ] 24
37 + 26 - x + 24 = 75
x = 12
1. either not on the football team OR on the baseball team
The set of people on the baseball team is a subset of the people not on the football team.
probability = (37 + 24)/75 = 61/75
2. at least on the baseball team OR not on the football team
This problem has the same answer as #1. (The wording is kind of confusing; I don't think "at least... or" has any difference from "either... or".)
3. either on the football team OR not on the baseball team
The set of people on the football team is a subset of the people not on the baseball team.
probability = (26 + 24)/75 = 50/75 = 2/3
4. at least on the football team OR not on the baseball team
This problem has the same answer as #3.
5. neither on the football nor the baseball team
This information was given in the problem.
probability = 24/75 = 8/25