I have a Database in which I keep track of all the toner for my company. I
list each box as it arrives with a number, and record it (1,2,3...345,346,
etc.). When it arrives, I record the date in one column, when I install it in
a machine, I record that date in the next column, and when I replace it with
a new one, I record that date in the next column. It looks something like
this:

A B C D E
F G
1 Ref # Toner Arrived Installed Machine# Replaced
Toner Life
2 1 C4127X 1/26/05 2/17/05 10185268 3/14/05
25

I have 62 different machines, and 50 types of toner and other supplies. I
maintain a fairly good JIT ordering system for this stuff, but i want to make
it one step better.
What I want to be able to do is display on a list of all the different
machines (several machines use the same type of toner) the most recent date
of installation for each machine, then use that number to determine how many
days are left on that installation, based on the average number of days in
the "Toner Life" column. I have already figured the average, but I need to be
able to pull out the date of the most recent installation for each machine,
and plug that into a formula. How do I retrieve that info for each machine?
I know this sounds crazy, but any help would be appreciated.

Thanks!