in this diagram, m DCB = ???

Answer:
56°
Step-by-step explanation:
The two marked angles are supplementary, so total 180°.
(2x +8) +(x -2) = 180
3x +6 = 180 . . . . . . . . . . collect terms
x + 2 = 60 . . . . . . . . . . . divide by 3
x = 58 . . . . . . . . . . . . . . subtract 2
∠DCB = x-2 = 58 -2
∠DCB = 56