1. The problem is to understand the variable $x$ and its role in algebra. 2. In algebra, $x$ is commonly used as a variable representing an unknown value. 3. Variables like $x$ can take on different values depending on the equation or expression. 4. For example, in the equation $x + 3 = 7$, we solve for $x$ by subtracting 3 from both sides: $$x = 7 - 3$$ 5. Simplifying, we get: $$x = 4$$ 6. Thus, $x$ represents the number 4 in this equation. 7. Variables are fundamental in expressing general mathematical relationships and solving problems.