Answer:
x = 6
Step-by-step explanation:
These triangles are similar shapes. They have the same shape but different sizes. This means there exists a scale factor between side lengths of the two triangles. They are related. You can find a missing side length by writing a proportion between the sides of each triangle.
[tex]\frac{x}{x+2}=\frac{9}{12}\\ 12(x) = 9(x+2)\\12x = 9x + 18\\3x = 18\\x = 6[/tex]
