A survey of 130 freshmen business students at a local university produced the results listed below. How many students took only psychology?

25 took history;
23 took science;
22 took psychology;
15 took history but not science;
10 took science and psychology;
11 took history and psychology;
4 took all three

To find the number of students who took only psychology, we need to subtract the students who took psychology and one other subject from the total number of students who took psychology.

22 students took psychology in total
10 took science and psychology
11 took history and psychology
4 took all three subjects

So, the number of students who took only psychology is:

22 - 10 - 11 - 4 = -3

This result doesn't make sense, as we can't have a negative number of students. This discrepancy suggests that there may be an error in the data provided or in the way the question is being approached.