Of the 130 students who took a mathematics exam, 90 corectly answered the
first question, 62 correctly answered the second question, and 50 correctly
answered BOTH questions. 


The universal set is all students taking the exam. (n(U) = 130.)
The two sets are:

A = students who answered question 1 correctly. (n(A) = 90)
B = students who answered question 2 correctly. (n(B) = 62).

This information alone is not sufficient to fill in the basic regions.