.
A + B = 180 degrees.
78 + B = 180 degrees.
B = 180 - 78 degrees.
B = 102 degrees.
Solved.
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To learn about supplementary angles, read the lessons
- Angles basics
- Vertical angles
- HOW TO solve problems on supplementary, complementary or vertical angles - Examples
- Solved problems on supplementary and complementary angles
in this site.
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