calculating # of days since install with no remove

Question for you gurus here:

I have another conditional arithmetic question where I want to determine the # of days for all order#'s that show "add" but that do not have a "remove".

I am assuming it will be variation of the following formula Mr. NigelBloomy & Oeldere demonstrated last week but I am having a tough time determining which part of that very elegant formula that needs to be revised to produce the proper result: =IF(COUNTIF($B$2:B2,B2)>1,ABS(A2-INDEX($A$2:$A2,MATCH(B2,$B$2:B2,0))),"")

Attachment 399851