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Clearly, 20° is the complement of 70° and 70° is the complement of 20°.

Thus, the complement of angle 53° = 90° - 53° = 37°.

Supplementary Angles:

Two angles are called supplementary angles, if the sum of the two angles is two
right angles i.e. 180°.

Each angle is called the supplement of the other.

Example: 30° and 150° are supplementary angles, because 30° + 150° = 180°

6. Adjacent Angles: Two angles are said to be adjacent, if they have a common
vertex, a common arm and their non-common arms are on different sides of the
common arm.
∠ABD and ∠DBC are the adjacent angles. Ray BD is their common arm and point
B is their common vertex. Ray BA and ray BC are non-common arms.

Note: ∠ABC = ∠ABD + ∠DBC

 Adjacent angles can be a complementary angle or supplementary
angle, when they share the common vertex and side.

Properties of Adjacent Angles

Some of the important properties of the adjacent angles are as follows:
Two angles are adjacent-angles, such that

 They share the common vertex.
 They share the common arm.
 Angles do not overlap.
 It does not have a common interior-point.
 There should be non-common arms on both the sides of the common arm.