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: $$x + 3 = 7$$ $$x + \cancel{3} = 7 - \cancel{3}$$ $$x = 4$$ 5. This means $x$ equals 4 in this context. 6. Variables are fundamental in expressing general mathematical relationships and solving equations.