Calculating Angle to True North

G-Day Excel forum.

I'm struggling to wrap my head around some relatively simple trigonometry, I'm attempting to calculate the bearing of a vector linking two sets of Easting/Northing coordinates and while I've found no shortage of equations online that should provide an answer, none seem to work in my excel sheet. The data comes from the southeastern hemisphere (i.e. Outback Australia) and my answer is needed in degrees to true north, I've attached a copy of my previous attempts to this post but I've got no idea where I'm buggering it up. If anyone out there could provide me with an equation for these data and the equivalent excel code I'd greatly appreciate it.

Cheers