112 Students
69 studied in the library
58 studied on union
25 studied in both
I do not understand the question very well but I'll give it my best shot
From what I understand, all you need to do is :
[tex]112 - 25[/tex]
112 from the total students and 25 from the students who studied in union and the library
So you solve it:
[tex]112 - 25 =87[/tex]
Hope this Helps!