1. Given (12+3)x, we can sum the numbers in the parenthesis to get 15x
2. Given 12x+3x, we can factor x to get (12+3)x and get the same as 1.
3. Given (12+3x)x, we have to distribute the x and we have 
4. This expression is already simplified.
Answer:
is it a angel if so obtuse if not I am really sorry
Check the attachment for the answers. Click on it again to make it bigger.
The opposite of zero (0) is -0, which is always equal to zero~
If your solving for x then I’m pretty sure this is right