Here are the properties that justify each step in your expression:
Line 1: From \( 9(8 + 7x) \) to \( 9(7x + 8) \)
Property: Commutative Property of Addition
Justification: The Commutative Property of Addition states that the order of addition does not affect the sum. Therefore, \( 8 + 7x \) can be rearranged to \( 7x + 8 \).
Line 2: From \( 9(7x + 8) \) to \( 63x + 72 \)
Property: Distributive Property
Justification: The Distributive Property allows us to multiply each term inside the parentheses by the factor outside. Thus, multiplying \( 9 \) by \( 7x \) yields \( 63x \) and multiplying \( 9 \) by \( 8 \) yields \( 72 \).
In summary:
- Commutative Property of Addition for Line 1.
- Distributive Property for Line 2.