Which number expression represents 1/2 the sum of 7 and 5 please help

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

Need on this one asap im almost done with this subject

Which expression is a factor of 12x2 + 29x – 8? x – 8 2x – 1 3x + 8 4x + 1