Vertical angles ate those that ate directly across from each other and share the same vertex. An example of this would be angles 5 and 7. These types of angles are also congruent, so angles 5 and 7 could be your congruent pair or another set of vertical angles like 1 and 3. A linear pair is two angles that together are a line. Basically, they are next ro each other (divided only by another vector) and are supplementary, adding up to 180 degrees. An example of this in the image is angles 1 and 2.
algebra, is a type of math.
By definition of absolute value, if 
, then 
, so
On the other hand, if 
, then 
, and
I think it is going to be 3. please let me know if you need more information
