Which one does not belong 3: 4, 9: 12, 12: 15, 12: 16 and why

Simonne used the following steps to simplify the given expression. 12 - 3(-2x + 4) step 1: 12 + (–3)·(–2x) + (–3)·(4) step 2: 12 + 6x + (–12) step 3: 12 + (–12) + 6x step 4: 0 + 6x step 5: 6x what property of real numbers was used to transition from step 3 to step 4? a. identity property of addition b. inverse property of addition c. associative property of addition d. commutative property of addition

What is the solution set of the quadratic inequality x2- 5< 0? o {xl-55x55{x- 155x55){xl -55x5 15){x1 - 15 sx5/5)

How do you solving the solution of each system using elimination?