9514 1404 393
Answer:
36
Explanation:
Let n represent the number of stickers Ms Galinia has. Then the number of students is ...
(n -12)/3 . . . for first distribution of stickers*
(n +4)/5 . . . for the second distribution of stickers
Since the number of students has not changed, we can equate these values:
(n -12)/3 = (n +4)/5
5(n -12) = 3(n +4)
5n -60 = 3n +12
2n = 72
n = 36
Ms Galinia has 36 stickers.
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* If Ms Galinia has 12 left over after giving 3 to each student, then subtracting 12 from her number of stickers will give a number that is 3 times the number of students. Dividing (n-12) by 3 will give the number of students. Similar reasoning can be used for the 5-per student distribution.
One could write equations using a variable for the number of students, or variables for both students and stickers. Since we only need to know the number of stickers, it seemed reasonable to use one variable for that.