Algebra-1

The correct answer is B. variable.

In mathematics, a symbol for an unknown value is typically referred to as a variable. Variables are represented by letters, such as a, x, or y, and they can take on different values. Variables are used to express general relationships and allow for flexibility in mathematical expressions and equations.

For example, in the equation 2x + 3 = 7, the variable x represents the unknown value that we are ...