Answer:
x = 8
Step-by-step explanation:
Since the triangle is isosceles then the 2 legs are congruent.
Given the perimeter is 66, then sum the 3 sides and equate to 66, that is
x + 4x - 3 + 4x - 3 = 66 , that is
9x - 6 = 66 ( add 6 to both sides )
9x = 72 ( divide both sides by 9 )
x = 8
