Respuesta :

sqdancefan

Answer:

  m∠ABD = 20°

Step-by-step explanation:

The bisector makes angles ABD and BDC congruent, so ...

  7x -1 = 4x +8

  3x = 9 . . . . . . add 1-4x to both sides

  x = 3

  m∠ABD = (7x-1)° = (7·3 -1)°

  m∠ABD = 20°