Question

4. Indicate which property is illustrated in Step 1.

Step 1 12 - 8x - 12 + 9x = (12 - 8x) + (-12 + 9x)
Step 2 = (12 - 8x) + (9x - 12)
Step 3 = 12 + (-8x + 9x) - 12
Step 4 = 12 + (-8 + 9)x - 12
Step 5 = 12 + x - 12
Step 6 = x + 12 - 12
Step 7 = x + 0
Step 8 = x

identity
distributive
associative
commutative