I have no idea how to attack this problem!!!! Can I get a step by step please?

Answer:
b. 25
Step-by-step explanation:
By the property of intersecting secant and tangent at a point on the circle.
[tex]m\angle KLM = \frac{1}{2}(\overset{\frown}{KJM})\\
\therefore 4x° = \frac{1}{2}\times (12x - 100)°\\
\therefore 4x° = \frac{1}{2}\times 2(6x - 50)°\\
\therefore 4x° = (6x - 50)°\\
\therefore 4x° = 6x° - 50°\\
\therefore 50°= 6x° - 4x°\\
\therefore 50°= 2x°\\
\therefore 2x = 50\\
\therefore x = \frac{50}{2} \\ \huge \red{ \boxed{\therefore x = 25 }}[/tex]