EXTENSION: Reflection in y=mx (NJT)

What stays the[b] same[/b] and what [b]changes[/b] as you move the points around?[br]What happens when you change the value of m using the slider?[br]Are there any points that do not move under this transformation?[br]Where would the co-ordinate (x,y) map to?
[color=#0a971e]Created by N.Trubridge[/color]

Information: EXTENSION: Reflection in y=mx (NJT)