Answer:
12 students
Step-by-step explanation:
Given
Required
Determine the number of students that eat lunch once a week
In Sets;
If out of 9, at least 7 eats one a week then
9 - 7 eats lunch once a week
<em>In other words;</em>
2 out of 9 students eat lunch once a week
Number of students in this category is then calculated as thus;