Answer
associative property of addition
Work Step by Step
The associative property of addition says that the addends can be "associated" in any grouping without changing the result.
8 is associated with 5$\ \ \ \ \ \ \ \ \ \ \ $8 is assocaiated with 11
$\overbrace{(5+8)}+11\ \ \ \ \ \ =\ \ \ \ \ \ 5+\overbrace{(8+11)}$
$\ \ \ \ \ \ \ 13+11\ \ \ \ \ \ =\ \ \ \ \ \ 5+19$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 24\ \ \ \ \ \ =\ \ \ \ \ 24\checkmark$