I have no idea how to attack this problem!!!!

I'm assuming  here  that  the  arc MJL   =  ( 12x - 100)°

If so.....when a chord  meets a tangent, the angle formed  is  1/2 the intercepted arc  formed by the chord

This implies  that

4x  = (1/2) (arc MJL)

4x  = (1/2) ( 12x - 100)  multiply both sides by 2

8x  = 12x  - 100     rearrange as

100 = 12x - 8x

100 = 4x     divde both sides by 4

25  = x