Will mark brainliest, help me answer this question!

135 degrees

Step-by-step explanation:

Angle CBD is the sum of angle ABC and angle ABD, so we find these firstAn Isosceles triangle has 2 equal sides and 2 equal anglesIsosceles triangle theorem tells us that the 2 equal angles are respectively opposite the equal sidesSince triangle ABC has sides AB=AC, then angle ACB = angle ABC So knowing that angles of triangle add up to 180, thenNow we do the next triangle to get ABDSince triangle ABD has sides AB=BD, then angle BDA = angle BAD So knowing that angles of triangle add up to 180, thenNow we said, angle CBD is the sum of angle ABC and angle ABD, so