1. The problem is to solve for $x$ in the equation $ax + b = 0$ where $a$ and $b$ are constants. 2. The formula to solve a linear equation of the form $ax + b = 0$ is: $$x = -\frac{b}{a}$$ 3. Important rule: $a \neq 0$ because division by zero is undefined. 4. To solve, isolate $x$ by subtracting $b$ from both sides: $$ax = -b$$ 5. Then divide both sides by $a$: $$x = -\frac{b}{a}$$ 6. This gives the solution for $x$ in terms of $a$ and $b$. 7. Example: If $a=2$ and $b=4$, then $$x = -\frac{4}{2} = -2$$ This is the value of $x$ that satisfies the equation.