Chapter 1 - Introduction to Algebraic Expressions - 1.6 Subtraction of Real Numbers - 1.6 Exercise Set - Page 49: 105

$0$

The expression $a-(-b)$ simplifies to $a+b.$ The expression $a+(-b)$ simplifies to $a-b.$ Hence, the given expression, $ -93+(-84)-(-93)-(-84) ,$ simplifies to \begin{array}{l}\require{cancel} -93+(-84)-(-93)-(-84) \\\\= -93-84+93+84 \\\\= (-93+93)+(-84+84) \\\\= 0+0 \\\\= 0 .\end{array}