Respuesta :

Answer:

∠ABD  = 20

Step-by-step explanation:

BD is the angle bisector, ∠ABD = ∠CBD  

∠ABD + ∠CBD = 40

∠ABD  + ∠ABD  = 40

2∠ABD  = 40

∠ABD  = 40/2

∠ABD  = 20