Well, the shape is a quadrilateral since there are 4 sides. This means the sum of all the angles is 360°. So:
49° + 107° + 2D + D = 360°
Now solve for D:
3D + 156° = 360°
3D = 204°
D = 68°
Now C is 2 times that angle, so C will be:
C = 2(68°) = 136°
To check if we are right:
49° + 107° + 136° + 68° = 360°