i. Let the measure of the complementary angle be x°. 

∴ 40 + x = 90 

∴ 40 + x – 40 = 90 – 40 

….(Subtracting 40 from both sides) 

∴ x = 50 

∴ The measure of the complement of an angle of measure 40° is 50°.

ii. Let the measure of the complementary angle be x°.

∴ 63 + x = 90 

∴ 63+x-63 = 90-63 

….(Subtracting 63 from both sides) 

∴ x = 27 

∴ The measure of the complement of an angle of measure 63° is 27°.

iii. Let the measure of the complementary angle be x°. 

∴ 45 + x = 90 

∴ 45+x-45 = 90-45 

….(Subtracting 45 from both sides) 

∴ x = 45 

∴ The measure of the complement of an angle of measure 45° is 45°.

iv. Let the measure of the complementary angle be x°. 

∴ 55 + x = 90 

∴ 55 + x-55 = 90-55 

….(Subtracting 55 from both sides)

∴ x = 35 

∴ The measure of the complement of an angle of measure 55° is 35°.

v. Let the measure of the complementary angle be x°. 

∴ 20 + x = 90 

∴ 20 + x – 20 = 90 – 20 

….(Subtracting 20 from both sides) 

∴ x = 70 

∴ The measure of the complement of an angle of measure 20° is 70°.

vi. Let the measure of the complementary angle be x°. 

∴ 90 + x = 90 

∴ 90 + x – 90 = 90 – 90 

….(Subtracting 90 from both sides) 

∴ x = 0 

∴ The measure of the complement of an angle of measure 90° is 0°.

vii. Let the measure of the complementary angle be a°. 

∴ x + a = 90 

∴ x + a – x = 90 – x 

….(Subtracting x from both sides) 

∴ a = (90 – x) 

∴ The measure of the complement of an angle of measure x° is (90 – x)°.