Need Help with Formula

Hello,
I'm not great at this and not sure this will even work. Ok, here goes;
In a certain cell I input manually a productivity number daily.
On certain occasions I will have to input a variation of Indirect Time in a different cell that needs to change the productivity number i input.
So, if AM3<0, then I would like AI3 to stay the same as I inputted it, but if AM3>0 then I would like AL3 to be divided by (AJ3-AM3) and the answer to be put in AI3.

Is this possible?