Where are these formulas derived from?

[Hutchoo]

Hey guys, I have a SAC on Materials and their use in structures and it's essentially based on finding the deflection of certain materials lalala. I'm not concerned about the prac as much as the methods we're using to actually get the required answers.We're given two formulas:
  Method 1
.; Method 2

These are seen in the picture (attached) but I typed them just to be sure you can see it properly

The definition of W, L, Y, B etc. are given in these two links. The experiments that are used in relation to the methods are also shown in the two links.
http://tinypic.com/r/icvg9x/6
http://tinypic.com/r/2mpbzis/6
This isn't cheating (we're allowed to research on our own, but I can't find anything helpful in regards to my problem)

[Phy124]

Not sure that this will help much but one of those equations is derived from two other equations:

Deflection on a beam is given by;

Inertia of a rectangular beam is given by;