Hi, i need a more complex average code.
I have this range "P4:BM4", with filled with numbers, and every week i add
some numbers (km).

ex: WEEK 1 (W1)
P Q R S T U V W....
W1 W2 W3 W4 W5 W6 W7

150 250 350 450 550 650 750

I need some average code that return in this case, 100.
I need the average km. a car is making, and i have cars km once a week;
something like...=average (first week minus second week) (second minus
third) (third minus fourth)....etc. I weekly add km, so the code to calculate
everything in this range."P4:BM4"

Can this be done?
Thanks!