The associative property of addition is what specifically is being applied. There's a multiplication version of this property as well. The associative property is the idea where we can move parenthesis around to group terms in different ways, and still get the same result regardless of what we did with the parenthesis.
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The associative property only works with addition and multiplication. Something like subtraction will be a different story
Eg: 1-(2-3) is different from (1-2)-3, so a-(b-c) is not the same as (a-b)-c
