The given triangles are congruent by HL property
Triangle ADC is congruent to triangle ABC
In any congruent triangles corresponding sides and angles are equal.
So angle marked 4x and 6x-58 are equal
We can form an equation
6x-58=4x
Subtracting 4x both sides and adding 58 both sides
6x-4x=58
2x=58
Dividing both sides by 2
x=29
Option D is right answer
