Conditional Formatting for cells with formulas

[Manyfaces]

I'm using three conditional formats within a worksheet list. I need a
fourth. "N/A". The first 3 conditions point to - "cell value" is "equal to"
+ format color. ("R" for red; "A" for Amber; "G" for Green). The formula
bar reads: =LOOKUP(B1/A1,{0,"R";0.65,"A";0.8,"G"}) How can I create a new
formula that shows the "N/A" while limited to 3 conditions?

Assumptions:
Red = <65%
Amber = >66%-<79%
Green = >80%
N/A = Does not Apply

Thanks

 

[Peo Sjoblom]

=IF(ISNA(your_formula),"Does Not Apply",your_formula)