Chapter 2 - Equations, Inequalities, and Problem Solving - 2.1 Solving Equations - 2.1 Exercise Set - Page 86: 15

a solution

Substituting $ x=-2$ to the given equation, $ x+7=3-x $, then \begin{array}{l} -2+7=3-(-2) \\\\ 5=3+2 \\\\ 5=5\text{ (TRUE)} .\end{array} Since the solution above ended with a $\text{ TRUE }$ statement, then the given value of the variable is $\text{ a solution }$ to the given equation.