The Associative Property of Addition states that the way in which numbers are grouped in an addition problem does not change the sum.
Using this property, you can rewrite the expression \( 3x + (2y + z) \) by regrouping the terms. One way to do this is:
\[ (3x + 2y) + z \]
So, the expression \( 3x + (2y + z) \) can be rewritten as \( (3x + 2y) + z \) using the Associative Property of Addition.