Variables and constants are two important parts of algebra. They each have their own special job.

Variables are like letters, such as $x$, $y$, or $z$. They stand for numbers we don’t know yet. Using variables helps us write general statements and equations.

For example, in $2x + 3$, the letter $x$ can be any number. If we say $x = 5$, we can work it out: $2(5) + 3 = 10 + 3 = 13$.

On the other hand, constants are numbers that stay the same no matter what. In the same example, $3$ is a constant. It will always be $3$, no matter what we choose for $x$.

When we put variables and constants together in an expression, they help us show relationships. For example, in the equation $y = 2x + 1$, the number $2$ is a constant that decides how steep the line is, and $1$ is a constant showing where the line crosses the y-axis. If we plug in $x = 3$, we find $y = 2(3) + 1 = 7$.

To sum it up, variables give us the freedom to represent different numbers, while constants keep our expressions connected to specific numbers. Knowing how variables and constants work together is important for solving algebra problems and understanding real-life situations.