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
