The two angles are a linear pair.
(Explanations down below!)
Linear pair angles must add up to 180 degrees. You can tell that the two angles add up to 180 degrees because they form a straight line (which is 180 degrees).
Complementary angles add up to 90 degrees. The two angles are not complementary because they do not form a 90 degree angle (right triangle, square in corner, like a L shape).
Vertical angles are opposite each other and are equal to one another. These angles are adjacent to each other and do not look similar.
Answer:

Step-by-step explanation:
The LCM of 14, 21 and 6 is 42
We require to change the fractions to fractions with a denominator of 42
+
+ 
=
+
+
← add the numerators, leaving the denominator
= 
=
← divide both values by 2
=
← in simplest form
Answer:
pretty sure is the first one
Step-by-step explanation:
a proportional relationship is a straight line that passes through the origin
Answer:
(6,-2.5)
Step-by-step explanation:
The formula for the midpoint between two points is:

Now we substitute
We have than (9, -1) is
and (3, - 4) is 
So:

So, we have:

<h2>(6,-2.5)</h2><h2 />
I can do a graphic explanation if you want.