Question

Indicate which property is illustrated in Step 3.

Step 1= 12 + 9x - 12 - 4x + 3 = 12 + (9x - 12) - 4x + 3
Step 2 = 12 + (-12 + 9x) - 4x + 3
Step 3 = [12 + (-12)] + (9x - 4x) + 3
Step 4 = 0 + (9x - 4x) + 3
Step 5 = (9x - 4x) + 3
Step 6 = (9 - 4)x + 3
Step 7 = 5x + 3

Answer 1

Step 3 is the associative property of addition.
The 12 and -12 are grouped together.