Indicate which property is illustrated in Step 4.

Step 1 6 - 9x - 6 + 10x = (6 - 9x) + (-6 + 10x)
Step 2 = (6 - 9x) + (10x - 6)
Step 3 = 6 + (-9x + 10x) - 6
Step 4 = 6 + (-9 + 10)x - 6
Step 5 = 6 + x - 6
Step 6 = x + 6 - 6
Step 7 = x + 0
Step 8 = x

commutative
distributive
associative
identity

Question

Indicate which property is illustrated in Step 4.

Step 1	6 - 9x - 6 + 10x	=	(6 - 9x) + (-6 + 10x)
Step 2		=	(6 - 9x) + (10x - 6)
Step 3		=	6 + (-9x + 10x) - 6
Step 4		=	6 + (-9 + 10)x - 6
Step 5		=	6 + x - 6
Step 6		=	x + 6 - 6
Step 7		=	x + 0
Step 8		=	x

    commutative
    distributive
    associative
    identity

directrix · Answer

The question is how to get from:

6 + (-9x + 10x) - 6 to  6 + (-9 + 10)x - 6

directrix · Answer

Both look quite similar other than an x has been factored out of (-9x + 10x). 

@Starr_Dynasty   We looked at that property a few problems back. Do you remember it?