Answer:
x is 3
Step-by-step explanation:
You use proportions to figure out x, what you first do is set up the proportion of the big triangle, then the small triangle.
[tex]\frac{(9+3)}{3}[/tex]= [tex]\frac{12}{x}[/tex]
By setting up this proportion, you would then cross multiply, and get 12x = 36. This is when you divide by 12 on both sides and get x=3
