Can you guys please help i don't get this: sides of triangle

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

Evaluate the expression for the given value of the variable. | ? 4 b ? 8 | + ? ? ? 1 ? b 2 ? ? + 2 b 3 -4b-8+-1-b2+2b3 ; b = ? 2 b=-2

Which of the following constants can be added to x2 - 3x to form a perfect square trinomial?