Respuesta :

Answer:

x = 3

Step-by-step explanation:

This is an isosceles triangle.  Two angles (D and F) are equal because the sides opposite them are equal (or vice versa).

Thus, side DE = side EF, or

12x - 8 = 4x + 16

Combining like terms:  8x = 24

Thus, x = 24/8 = 3

x = 3