Final answer:
The measure of a supplementary angle to one measuring 100° is incorrect as supplementary angles must sum to 180°. To find the measure of a supplementary angle, subtract the given angle from 180°.
Step-by-step explanation:
The query is related to the concept of angles, specifically supplementary angles. When two adjacent angles are supplementary, they add up to 180°. However, in this particular case, the question mentions the sum of these two angles being only 100°, which seems like a misunderstanding. To clarify, two angles that add up to 100° are not supplementary by definition. If we are looking for the measure of an angle that is supplementary to another angle and their sum is given as 100°, then there is a mistake because supplementary angles must sum up to 180°.
If the student meant to say that the sum of a supplementary angle pair is 100°, then this would be incorrect. However, if the question is instead asking for the measure of an angle that is part of a pair of supplementary angles that sum to 180°, then we would need to subtract the given angle from 180° to find the measure of the unknown angle. For example, if one of the angles was given as 60°, then the measure of its supplementary angle would be 180° - 60° = 120°.