The measure of an angle is 4y. find the measure of its complement.
a) 90 - 4y
b) 90 + 4y
c) 180 - 4y
d) 180 + 4y

Complementary angles are angles whose measure add up to 90°.

So, if one angle is 4y, the complementary angle is 90°- 4y. Choice A.

Complementary angles does not necessarily need to share a line or vertex. As long as both angles have a sum of 90°, then, they are complementary angles.

Angles who has a sum of 180° are called supplementary angles.