Respuesta :

Answer:

[tex]x=4[/tex]

Step-by-step explanation:

Cross-multiply to simplify:

[tex]\frac{x}{12}=\frac{3}{9},\\9x=12\cdot 3,\\9x=36[/tex]

Divide both sides by 4 to isolate [tex]x[/tex]:

[tex]x=\frac{36}{9}=\boxed{4}[/tex]