Final answer:
Values in mathematics can be numerical and represented by variables, which can be positive or negative. Numerical variables can be compared using mathematical operations, whereas categorical variables cannot.
Step-by-step explanation:
Values can refer to different types of data in mathematics. When talking about numerical values, these are quantities that can indeed be both positive or negative, and they can be represented using variables. Variables serve as placeholders for these values and can be denoted by symbols, often letters like X, Y, or Z. Numeric variables can be involved in mathematical operations, allowing them to be compared relative to one another. However, it's important to note that while numerical variables can represent numerical quantities and thus be subjected to mathematical operations, not all values are numerical. Categorical variables, for example, classify data into groups but do not possess numerical qualities and thus mathematical operations are not applicable to them in the same way.