I'm new to Access and VBA. (I've been working with Pick/Universe forever.)
I'm about going nuts trying to figure out something that should be (and most
likely is) very simple.

I have a form that reads and writes data from/to a table (call it
mainTable). It also reads data from a 2nd table (call it secondTable). What
I can't figure out how to do is update an item in secondTable from a
calculation in the mainTableForm. Specifically, I would like to take a value
from secondTable, subtract a value from mainTable and write the new value
back on the same field in secondTable.

Suggestions?

Bob