What does best estimate of a product mean?

With #! i’ve tried to figure it out but i can’t.

Plzz ! 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? yes or no? = explain your mathematical thinking/show your work:

Write an expression that is equivalent to ( 3+14)+27.