Respuesta :

9514 1404 393

Answer:

  x = 4

Step-by-step explanation:

Corresponding segments of similar triangles are proportional. Here, the similar triangles are ...

  ΔABC ~ ΔADE

so the relationship between the sides is ...

  BC/BA = DE/DA . . . . . . we put the unknown value in the numerator

  x/4 = 12/(4+8)

  x = 4(1) = 4

The length of side x is 4.