10x+8=-2 how do you solve this i need

In a column proof the right column states your reasons

The length of the line segment ac is 8x-9 what is the value of x

If you were constructing a triangular frame, and you had wood in the length of 4 inches, 4 inches, and 7 inches, would it make a triangle? would you be able to create a frame from these pieces of wood?