Final answer:
The measure of m∠DBC is 100°, assuming that ∠ABC and ∠DBC form a linear pair. Subtracting m∠ABC from 180° gives the measure of ∠DBC.
Step-by-step explanation:
If m∠ABC = 80°, we need to determine the measure of m∠DBC. Without additional context or a diagram, it can be difficult to deduce the relationship between ∠ABC and ∠DBC. However, assuming that A, B, C, and D are points on a line in that order, we can infer that ∠ABC and ∠DBC form a linear pair. A linear pair is a pair of adjacent, supplementary angles, meaning their measures add up to 180°.
With ∠ABC measuring 80°, we can find the measure of ∠DBC by subtracting this from 180°:
180° - 80° = 100°. Therefore, the measure of ∠DBC is indeed 100°, and they form a linear pair. Hence, the correct answer is (c) 100°; linear pair angles.