1. The problem is to find the value of $x$ that satisfies the equation $x + 7 = -9$. 2. To solve for $x$, we use the rule of isolating the variable by subtracting 7 from both sides of the equation. 3. Write the equation and subtract 7 from both sides: $$x + 7 - 7 = -9 - 7$$ 4. Simplify both sides: $$x + \cancel{7} - \cancel{7} = -9 - 7$$ $$x = -16$$ 5. Therefore, the value of $x$ that makes the equation true is $-16$. Final answer: $x = -16$