What points can I write about/ what should I write about?

What is the value of x in the equation 2(x-4) = 4(2x + 1)?

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

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