ANSWER
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Ratio of 8th graders to 7th graders = 3 : 2
Let the number of graders be 3x and 2x
Number of 8th graders = 18
So , 3x = 18
x = 18/3 = 6
Number of 7th graders = 2 × 6 = 12
Ratio of 6th graders to 7th graders = 5 : 4
Let the number of graders be 5a and 4a
Number of 7th graders = 12
So , 4a = 12
a = 12/4 = 3
Number of 6th graders = 5×3 = 15 ANS
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#BE BRAINLY
:) Hope this answers your question :)
x = total amount of gumballs
let's start subtracting the balls she's giving away


and we also know that after all that has been subtracted, she's only left with 5, so we can say that

the perimeter is:
4(4x - 6)
Applying distributive property:
4(4x) - 4(6)
16x - 24
Then, the perimeter can also be represented by 16x - 24 because 4(4x - 6) can be simplified to 16x - 24