Explanation:
No of Student in Debre Berhan University - 80 students
No of student good in mathematics - 45 student's
No of students good in mathematics and English -15
No of students good in mathematics and psychology -13
No of students good in English and psychology -16
No of students good in psychology -20
no of student good in mathematics -45+15+13
-75
therefore no of student good in math is 75 .
pls mark me branilest