Answer:
60°
please look into the solution down here.
Explanation:
since BD bisects it, then the angles should be bisected symmetrically, or in other words, ANGLE ABD = angle DBC,
hence,
4x = 2x +30
2x = 30
x = 15
therefore, angle DBC = 2x + 30 = 2(15) + 30 = 60°.