When you are creating your segment, there should be a gear in the right
corner of the segment. Click on this and Exclude will be an option. Then
set the variable with equals and then the page names will be excluded
from the Workspace table.
Can you post an image of what the segment looks like from the Segment
Creation page? It is difficult to tell from the information that you
provided but it sounds like you need to use exclude instead of not does
I am not exactly sure what it is your trying to calculate. The values in
account balance is a bucket for the volume of accounts that have that
balance (so you have 88 accounts with a 20 balance). If you wanted to
sum the 88 accounts with a balance of 20 for a value of 1760, then I
would create a calculated metric of multiplying the two variables.