What does the equation A + (B + C) = (A + B) + C illustrate?

The equation A + (B + C) = (A + B) + C illustrates the Associative Property of addition. This property states that when adding three or more numbers, the way in which the numbers are grouped does not affect the sum.

In this equation, whether you first add B and C together and then add A, or first add A and B together and then C, you will arrive at the same total. This emphasizes the flexibility in grouping, which is the essence of the Associative Property.

Understanding this property is crucial in mathematics because it allows for reorganization of terms in calculations, which can simplify problems and make mental calculations easier.