The sum of the measures of complementary angles is 90º.

(i) 20°

Complement = 90° − 20°

= 70°

(ii) 63°

Complement = 90° − 63°

= 27°

(iii) 57°

Complement = 90° − 57°

= 33°

The sum of the measures of supplementary anglesis 180º.

(i) 105°

Supplement = 180° − 105°

= 75°

(ii) 87°

Supplement = 180° − 87°

= 93°

(iii) 154°

Supplement = 180° − 154°

= 26°

The sum of the measures of complementary angles is 90º and that of supplementary anglesis 180º.

(i) 65°, 115°

Sum of the measures of these angles = 65º + 115º = 180°

∴ These angles are supplementary angles.

(ii) 63°, 27°

Sum of the measures of these angles = 63º + 27º = 90°

∴ These angles are complementary angles.

(iii) 112°, 68°

Sum of the measures of these angles = 112º + 68º = 180°

∴ These angles are supplementary angles.

(iv) 130°, 50°

Sum of the measures of these angles = 130º + 50º = 180°

∴ These angles are supplementary angles.

(v) 45°, 45°

Sum of the measures of these angles = 45º + 45º = 90°

∴ These angles are complementary angles.

(vi) 80°, 10°

Sum of the measures of these angles = 80º + 10º = 90°

∴ These angles are complementary angles.

Let the angle be x.

Complement of this angle is also x.

The sum of the measures of a complementary angle pair is 90º.

∴ x + x = 90°

2x = 90°

$x=\frac{90°}{2}=45°$