Answer:
x = 9
Step-by-step explanation:
The outer and inner triangles are similar, thus the ratios of corresponding sides are equal, that is
[tex]\frac{8}{8+4}[/tex] = [tex]\frac{x-3}{x}[/tex] , that is
[tex]\frac{8}{12}[/tex] = [tex]\frac{x-3}{x}[/tex] ( cross- multiply )
12(x - 3) = 8x
12x - 36 = 8x ( subtract 8x from both sides )
4x - 36 = 0 ( add 36 to both sides )
4x = 36 ( divide both sides by 4 )
x = 9
