Can total sum from formula column on one board be deducted from a Numbers column in an item on another board?

Hi, I looked at this link, and it almost worked, but basically, I want to be able to use Time Tracking to track length of support, each time support is provided, a new Item is created. Next to the time tracking column, there is a formula column, which totals all the time tracking items and gives a total. I want to be able to deduct this total from a single Number column in an item on another Board, but I can use the Match template, because it doesn’t seem to be able to get the formula sum to deduct from a numbers column.

Basically I want this sum (time tracking to formula)

To be deducted from these hours, but not in total, Fred’s hours are the target.

In summary, I want multiple items to be tallied, and then deducted from one specific Numbers columns on another board.

Hope that makes sense.

Thanks heaps!