Final answer:
The equation 7 + 9 + 3 = 7 + 3 + 91 demonstrates the commutative property of addition.
Step-by-step explanation:
Associative Property of Addition: This property deals with grouping numbers during addition. The equation involves only addition and does not demonstrate the associative property because the grouping of numbers is not changing.
Associative Property of Multiplication: This property is not applicable in this case, as the equation involves only addition.
Commutative Property of Addition: This is the correct choice. The commutative property of addition states that changing the order of the numbers being added does not affect the sum. In this case, swapping the positions of 9 and 3 on one side of the equation doesn't change the overall sum.
Commutative Property of Multiplication: This property is not applicable as the equation involves only addition.
So, the correct answer is 3. Commutative Property of Addition.