The equation \((x \cdot 3)5 = 5(x \cdot 3)\) is a test case for the Commutative Property of Multiplication. This property states that the order in which numbers are multiplied does not change the product. In this case, you are testing whether changing the arrangement of the factors (5 and \(x \cdot 3\)) affects the result. Therefore, the correct answer is:
the Commutative Property of Multiplication.