Answer: D) Complementary angles
angle b = 26
Complementary angles always add to 90 degrees
You can think of the "co" in complementary referring to "corner", since both words start with "co".
In contrast, supplementary lines form a straight angle (ie the angles add to 180). "Supplementary" and "straight" both start with S to help remember the term.
The angles shown are adjacent, but the term complementary is a better description I think. The angles are not vertical angles.
Since b+64 = 90, this equation solves to b = 26 after subtracting 64 from both sides.