Answer:
the measure of ∠D is 8°.
Explanation:
Since ∠C and ∠D are vertical angles, they have equal measure. So we can set their measures equal to each other and solve for x:
x + 16° = 4x - 5°
6x = 21°
x = 3.5°
Now we can find the measure of ∠D:
∠D = 4x - 5°
∠D = 4(3.5°) - 5°
∠D = 8°
Therefore, the measure of ∠D is 8°.