What is the measure of an angle if its two, adjacent, supplementary angles add up to 100°.

130 degrees.

To find the measure of the angle in question, we first need to understand the properties of adjacent and supplementary angles.

Adjacent angles are angles that share a common vertex and a common side. In other words, they are side by side.

Supplementary angles are two angles that add up to 180°. In other words, the sum of their measures is equal to 180°.

In this case, we are given that the two adjacent angles are also supplementary, and their sum is 100°. Let's call the measure of one angle x.

Since adjacent angles share a common side, their sum must equal 180°. Therefore, one angle is x and the other angle is 180° - x.

We are given that their sum is 100°, so we can set up the equation:
x + (180° - x) = 100°

Simplifying the equation, we have:
180° - x + x = 100°
180° = 100° + x

By subtracting 100° from both sides, we get:
80° = x

Therefore, the measure of the angle in question is 80°.

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