Seeking Help with a Formula

Registration date
Tuesday October 11, 2016
Last seen
October 11, 2016
First, thanks for taking the time to read this.
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?

Thank you very much in advance for any help that is provided.