Question 141063
What does the law of association mean? It means you can change the grouping of added or multiplied terms and still have the same result.

Given : {{{ r+(s+48) }}}

Since this equation hs the last two terms grouped and only three terms in it, the only other equation you can write using only association is 
{{{(r+s)+48)}}}

As you can see, the result for both equations is {{{r + s + 48 }}}