Three less than the square of a number

You are assembling pieces of an iron gate to complete a fence. the finished gate will look like the one below. in order to assemble the gate it is important to under how the pieces are related. part 1: how are pies 1 and 2 in the archway related? part 2: how are the rectangular sections 5 and 6 in the center of the gate related to each other?

Which of these tables represents a non-linear function?

If a || b and b | y, then ? a) x || y. b) x | a. c) a | y. d) a || y.