Respuesta :

Answer:

           x = 15 cm

Step-by-step explanation:

If triangle ABC is similar to triangle DEF, then:

                                                                    [tex]\dfrac{AC}{DF}=\dfrac{BC}{EF}[/tex]

Therefore:

[tex]\dfrac{x}{5}=\dfrac{12}{4}\\\\\dfrac{x}{5}=3\\\\x=15[/tex]