If the 2 base angles are congruent then the two opposite sides are congruent
This is called the leading term
To a higher number the six changes value in this number above
Assuming you want to find x?
You know that the angles at C and B have to be the same (6x) because it’s an isosceles triangle (as indicated by the lines going through AC and AB), and angles in a triangle add to 180*
So 3x + 6x + 6x = 180*
15x = 180*
x = 180*/15
x = 12*
