Hi there!
[tex]\large\boxed{x = 11}[/tex]
From the diagram, we can see that ΔAEF, and ΔACB are similar, isosceles triangles.
Therefore:
∠B and ∠F are congruent because they are corresponding angles, and ∠B and ∠E are congruent because of equal base angles in an isosceles triangle.
Therefore:
7x - 11 = 6x
Subtract 6x from both sides:
x - 11 = 0
Add 11 to both sides:
x = 11.
