Question 98048
This would be the associative property of addition because it states "for all real numbers a,b and c their sum would be the same regardless of their grouping."

So, {{{(a+b)+c=a+(b+c)}}}

In your equation {{{(8.9+2.4)+7.6=8.9+(2.4+7.6)}}}
{{{(11.3)+7.6=8.9+(10)}}}
{{{18.9=18.9}}}
Associative property of addition