Answer:
AC = 15 units
Step-by-step explanation:
Since BD is an angle bisector then it divides the opposite side into segments that are proportional to the other 2 sides, that is
[tex]\frac{AB}{BC}[/tex] = [tex]\frac{AD}{DC}[/tex] , substitute values
[tex]\frac{12}{18}[/tex] = [tex]\frac{6}{x}[/tex] ( cross- multiply )
12x = 108 ( divide both sides by 12 )
x = 9
Then
AC = 6 + 9 = 15 units
