I work at a gas station and i am trying to figure out the average cost of
fuel in my tank. I have the current volumes and past deliveries set up below.

A2=13485 (current Volume)
A3=4565 (fuel delivery1)
A4=6554 (fuel delivery2)
A5=9004 (fuel delivery3)
A6=4815 (Fuel delivery4)

I need to know how much fuel from each delivery is in the tank. I know I
have all the fuel from deliveries 1 and 2 and 2366 from delivery 3. But how
do i get the formula to only count 2366 gallons from 3 and 0 from 4?