Question

What is the length of AC ? Enter your answer in the box. =units

Answer 1

That's an isosceles triangle lying on its side.  The base angles (on the left) are marked equal, so we know the sides opposite them are equal.

That means that  . . . x+4 = 3x-8

Subtract 'x' from each side . . . 4 = 2x-8

Add  8  to each side . . . 12 = 2x

Divide each side by 2 . . . 6 = x