I have these two formulae, =K8+Y6-SUM(L8:X8) and =SUM(AA6+Y8-Z8), in an
accounting spread sheet. How can these formulae be made to reflect both
negative and positive amounts in the data cells they drawing data from.

As it stands now, if a given cell has a negative amount in it, e.g., P8 is
(2100.00), that negative amount is converted to a positive amount by both
formulae, thus a positive 2100.00 is added to the total rather than
subtracting the negative (2100.00) showing in cell P8.