Too many arguments

Trying to add an argument to an already working formula - see attached worksheet w/the formula/cell in question in yellow.

I need to add the following logic to the existing formula,

If L10="N", AND O30<L9, then O30-L9, otherwise, if L10="", then O31-L9.

I have tried AND, but I'm not entering something correctly.

Any guidance would be greatly appreciated!