Answer: 55 degrees
Step-by-step explanation:
Triangle ACE is isosceles, and so is triangle BCD because we have similar triangles (use the AA theorem to prove this).
The diagram shows angle ABD = 125.
Angle DBC = 180 - (angle ABD) = 180-125 = 55 degrees, which is also the measure of angle CDB because the base angles of isosceles triangles are congruent.