This is an equilateral triangle (as shown by the markings), therefore all sides have equal length.
XZ = ZY
[tex] \frac{1}{2} x + 8 = 2(x - 8)[/tex]
[tex] \frac{1}{2} x + 8 = 2x - 16[/tex]
[tex] \frac{1}{2} x + 24 = 2x[/tex]
[tex]24 = 1.5 x[/tex]
[tex]x = 16[/tex]
