Answer
Find out the how many students in your high school would you expect to pack their lunch.
To prove
Let us assume that the number of student pack their lunch be x.
Formula

As given
A news report says that 28% of high school students pack their lunch.
Your high school has 600 students.
Percentage = 28 %
Total value = 600
Part value = x
Put in the formula


x = 168
Therefore 168 students pack their lunch .