Question

Indicate which property is illustrated in Step 1.

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

associative
commutative
additive identity
distributive

Answer 1

it was just adding in parenthesis to group the equation
so associative

Answer 2

thank you @jigglypuff314

Answer 3

your welcome :)