Answer:
Supplement to ∠ABC: ∠DAB acts as a possible supplement
Explanation:
There are two approaches to this problem:
1. We can identify an angle by it's measure such that it adds to 180° when added to the m∠ABC
2. As this shape is a quadrilateral, we can tell that two adjacent angles are supplementary to one another, and thus can be identified as the supplement to ∠ABC
For the simplicity, lets take the second method into consideration. We see that ∠ABC is adjacent to the two angles - ∠BCD, ∠BAD. These angles can be rewritten as such: ∠DCB, ∠DAB. And, as we can see from the options, ∠DAB is one of them that may act as a supplement. Shall we check?
The m∠ABC is 110° (degrees) so that it's claimed supplement, ∠DAB should be 70° as to satisfy the first condition of adding to 180°. And, we can see from the diagram that 40° + 30° = 70° so that both "approaches" are met!