Get The Number In The Column To Its Left

I have a spreadsheet with 3 columns. The first column has a list of numbers, the second column has a list of numbers, and the third column has a code, one of which is “IP”

I want to look up IP, when I find it I need to get the number in the column to it’s left, on the same row. Then I need to look up that number in the first column (which will be on a separate row). I then need to change the word in the third column of that row to “Kit”.

Col. A has numbers
Col. B has numbers, some of which are the same as in Col. A, but not in the same row
Col. C has a code, one of which is ‘IP’

I want to look for ‘IP’ in column C. When I find it, I want to get the number corresponding number from Col. B (same row), then look up that number in Col. A. (remember, Col. A and Col. B have some of the same numbers, they are just not in the same row).

When I find that number in Col. A, I want to change the code that is in Col. C, from that same row, to read “Kit”

Example: I find “IP” in Col. C. The coinciding number in Col. B is “4630.0”. I find that number in Col. A (one row down) and need to change the “CP” in Col. C to “Kit”.

Col. A Col. B Col. C
12345.0 46730.0 IP
46730.0 CP – (this needs to be changed to “Kit”)