AP / AR Trigger for negitive numbers

Hey Gang, so I come to the experts for some advice, again.

I have a spread sheet with many cells (A:ZZ & 10 to 40009)

In column F, I have a drop down list giving 2 choices, AP & AR. These are the main triggers for what I need to happen.

When I select "AP" in column F, I need column I to see only a negative number (-$100), and at the same time in column M, I need it to see only a positive number ($100)

When I select "AR" in Column F, I need column I to see only positive number ($100), and at the same time in column N, yes N, I need it to see only a negative number (-$100)

there are other conditions to the cells I need, but those I have figured, its this one that is stumping me.

I have included a bit of an example with this question