Find the complement of the supplement of 145°.

Class 7Lines and AnglesLines and Angles

A35°
B55°
C125°
D215°

Step-by-Step Solution

Work from the inside out. Supplement of 145° = 180 − 145 = 35°. Complement of 35° = 90 − 35 = 55°. Trap: 35° is only the halfway answer — the question asks for the complement OF that result; 125° is 180 − 55, which comes from taking a supplement at the second step instead of a complement.

Answer: B) 55°

Key idea: Complementary and supplementary

Two angles are **complementary** if they add to 90°. So if one is 35°, the complement is 90° − 35° = 55°.

Two angles are **supplementary** if they add to 180°. So if one is 110°, the supplement is 180° − 110° = 70°.

The angles don't have to be next to each other — only their measures matter.

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