Answer:

Step-by-step explanation:
In order to figure out what number should go in the blank within the parentheses, we use the formula
, where b is the coefficient of the x term. In this case, b = -4. So, the number in the parentheses blank is:
.
Now, on the left, our parenthetical expression is:
. However, we're not done. The top and bottom equations still need to equal each other. Let's see if they are equal by expanding the
:
. Clearly, they're not the same because the top equation has a -32, whereas the bottom one has +4. So, in order to make these the same, we need to add or subtract something to the right side of the bottom equation.
What will make the left side have -32? If the right side has + 36:
. We can check this by subtracting 36 from both sides:
⇒
... and they match.
So, our final answer is: 
Hope this helps!