Answer:
42°
Step-by-step explanation:
[tex]m\angle ABD + m\angle DBC = m\angle ABC\\
2x + 2x - 3 = 81\degree \\
4x - 3 = 81\degree \\
4x = (81+3)\degree \\
4x = 84\degree \\
x = \frac{84}{4}\\
x = 21\\\\
m\angle ABD = 2x = 2*21\degree = 42\degree [/tex]
