## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$5+(m+r)$
The associative law of addition states that $a+(b+c)=(a+b)+c$ (where $a$, $b$, and $c$ are real numbers). That is, changing the grouping of numbers to be added does not affect the answer. Therefore, $(5+m)+r=5+(m+r)$.