The expression 3x - 2y represents a mathematical expression with variables x and y. Constants are values that do not change and are not associated with variables. In the expression 3x - 2y, there are no constants because both terms involve variables (3x involves x, and -2y involves y). If there were a constant term, it would be written without any variables attached, such as 3x - 2y + 5, where 5 is the constant term.
