I have a spreadsheets like this:

15-A $5 Unique $12
15-A $4 Dupe
15-A $3 Dupe
15-B $9 Unique $9
15-C $2 Unique $12
15-C $3 Dupe
15-C $7 Dupe


I want the add up the numbers for each unique package (i.e. create column
4). Any ideas?