Data duplication assistance

I have files with 30,000+ lines of data in many columns that I need to remove specific lines from. For instance; Column A will have dollar values. In the dollar values column there may be a negative number. I need to find a corresponding positive dollar value for that negative dollar value (i.e. -$123.45 and $123.45) and validate against two other columns. Once the positive dollar value is found (which there will be multiples of) I must verify the positive dollar value is for the same criteria in column C (i.e. a drug name) as well as be within 30 days of the date housed in column B for the negative dollar value. If there are multiple line items that meet the criteria of 1) negative and positive dollar values, 2) same drug name, and 3) within 30 days then I need to choose the line item with the closest date in column B. Once found and chosen then both line items (negative and positive) need to be either highlighted in yellow or moved to another tab.

Any help? Thanks

what about:
in a new blank col....(you choose the letter)

G2 = if(A2<0,"negative","") (this will show all negatives)
H2 = abs(A2) (to give you the positive value)
I2 = calculate days < 30 (to find days from the date)