Answer:
6
Step-by-step explanation:
Given an isosceles triangle the two sides opposite of congruent angles are equal to eachother, so you can create an equation setting the two sides equal to eachother and solve for x.
[tex]x+4=3x-8\\x=3x-12\\-2x=-12\\x=6[/tex]
The length of AC is simply x, therefore 6
