Answer:
[tex]\boxed{10}[/tex]
Step-by-step explanation:
The angle bisector divides the segments so those on one side of it are proportional to those on the other side of it.
(x+4)/8 = (2x+1)/12
12(x +4) = 8(2x +1) . . . . . multiply by 96
12x + 48 = 16x + 8 . . . . . eliminate parentheses
40 = 4x . . . . . . . . . . . . . . add -12x-8
10 = x . . . . . . . . . . . . . . . . divide by 4
