How to update absolute cell number

I have the following formula in a cell


Now, depending on a month G$31 will change, that is the last two digits will change. How to add an integer to
the cell address?
to get from G$31 --> G$29 for example. I tried substructionG$(31 -2) but it did not work.


So probably


if I understood correctly.

@erAck, yes this works! Thank you. I can’t upvote, don’t have yet 5 points.

Marking the answer as correct with the check mark is fine, thanks!