Let's remember the following definitions:
1. Vertical angles are those angles that are opposite to each other and share the same vertex. Their measures are equal (They are congruent).
2. A Linear pair of angles are those adjacent angles formed when two lines intersect each other. They are Supplementary, which means that they add up to 180 degrees.
For this case you can see two lines "l" and "m" that are cut by the line "n".
a) Based on the definitions shown above, you can identify this pair of Vertical angles:
[tex]\angle1\text{ and }\angle4[/tex]Because the are opposite and share the same vertex.
b) You can also identify this pair of angles that form a Linear pair:
[tex]\angle2\text{ and }\angle4[/tex]c) Since you know that Vertical angles are congruent, you can determine that this pair of angles are Vertical angles and congruent:
[tex]\angle6\text{ and }\angle7[/tex]Therefore, the answers are:
a)
[tex]\angle1\text{ and }\angle4[/tex]b)
[tex]\angle2\text{ and }\angle4[/tex]c)
[tex]\angle6\text{ and }\angle7[/tex]