VBA Code to Calculate Average of Every Row

Hello Excel Experts,

I have a spreadsheet (attached) where rows are days of the week; columns are houses and values are Volts.
The number of rows and columns can Change from time to time, so I want to know if there is a VBA that could do the following:

-On the first cell of the first empty cell found write "AVERAGE" and on the first empty cell of the next column "AVERAGE X ,25". (For the example sheet I attached, it would be on M1 and N1).
-Calculate the average of each complete row, starting at B2, post this average on M2 and then multiply this average by .25 and post on N2.
-Repeat on each row until there is no more data.

I have been trying to get this for a couple hours now, however from what I learned in the couple days barely allows me to look for the first empty column on the sheet.

Thank you very much in advance!

Jorge