Answer:
[tex]\boxed{\textrm{(A) Associative property}}.[/tex]
Step-by-step explanation:
While it may look like the associative property was correctly demonstrated, it was not. Generally, this property says that for [tex]a,b,c\in\mathbb{R}[/tex] we have:
[tex](a+b)+c=a+(b+c).[/tex]
Let [tex]a = 7[/tex], [tex]b = -x[/tex] and [tex]c=-5[/tex]. We then have:
[tex](7-x)-5 = [7+(-x)]+(-5) = (a+b)+c.[/tex]
Applying the associative property, we get:
[tex](a+b)+c = a+(b+c) = 7 + [-x + (-5)] = 7 - x - 5 = 7-(x+5).[/tex]
We now notice that the sign inside the parenthesis is wrong, so the answer is:
[tex]\boxed{\textrm{(A) Associative property}}.[/tex]
