Mis the midpoint of ab , am=3x 3, and ab=8x−6. what is the length of mb?

The question is asking to calculate the mid point of AB if AM = 3x^3 and AB 8x^-6 and find the length of MB and base on my computation, I would say that the answer would be 5x^-9.  I hope you are satisfied with my answer and feel free to ask for more if you have question and further clarification 

No a triangle cannot be formed because when you add the two smallest number together (which would be 11) the have to be bigger than the number it is "against" ( which would be 12)