Nested if, or

[Rosstamon]

Hello,
I have 2 columns with dates. Sometimes one column or both will have N/A in it or may be blank. I'm trying to figure out how to get:
(IF A1=N/A or if B1=N/A return a value of N/A) OR (if A1="" or if B1="" return a value of "") OTHERWISE B1-A1

I'm sure this is some sort of nested OR type statement but I'm having trouble figuring out the proper syntax. Any help would be most appreciated.

 

[RonB1111]

=if(or(a1="n/a",b1="n/a"),"n/a",if(or(a1="",b1=""),"",b1-a1))

 

[Rosstamon]

I was dancing all around that but just wasn't quite there. This works exactly like I was hoping. Very much appreciated.

 

[RonB1111]

You're welcome. Thank you for the feedback.