Given data:
The measure of the angle ABC is m∠ABC=85 degrees.
The expression for the m∠ABC is,
m∠ABC=m∠ABD+m∠DBC
85°=(4x+2)°+(8x-1)°
85°=12x+1
84°=12x
x=7°
The measure of the ∠ABD is,
m∠ABD=(4x+2)°
Substitute 7 for x in the above expression.
m∠ABD=(4(7)+2)°
=30°
Thus, the mmeasure of the ∠ABD is 30°
