For this question you will need to find out how many cookies each student eats. To find this, do 84 divided by 28. You will get 3. Since 28 is 2 less than 30, add 6 cookies for the two extra students. You will need 90 cookies.
First you need to figure out how many cookies will serve a single student. You divide 84 by 28 and get 3. So if 3 cookies serves an individual student, you multiply 3×30 and get 90. 90 cookies serve 30 students.
