What symbol, usually a letter, could represent a number?

• A. Variable
• B. Constant
• C. Parameter
• D. Coefficient

Answer: (A)

In algebra, a symbol that can stand for a number that may change is a variable. We typically use letters like x, y, or z to represent unknown values that can take on different numbers in different problems or in different parts of an equation. The idea is that the variable is not fixed—you’re solving for what number it represents in a given situation.

A constant, by contrast, is a fixed number that doesn’t change. A coefficient is the number that multiplies a variable (for example, in 3x, the 3 is the coefficient). A parameter can be a value that defines a family of relationships, but within a specific scenario it’s usually treated as a fixed value rather than the general symbol for an unknown that can vary. So the symbol that best fits “could represent a number and can vary” is the variable.