Recognize angle measure as additive. When an angle is decomposed into non-overlapping parts, the angle measure of the whole is the sum of the angle measures of the parts. Solve addition and subtraction problems to find unknown angles on a diagram in real world and mathematical problems, e.g., by using an equation with a symbol for the unknown angle measure.

Example Problems
and are supplementary angles.
measures .
What is the measure of
?
and are supplementary angles. measures . What is the measure of ?
and are supplementary angles.
measures .
What is the measure of
?
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