Format Cell fill based on contents of multiple other cells

I need to be able to change the fill color of several cells based on the values of multiple individual cells.

See attached example for a better explanation.

Thanks

welcome to the forum, nsmjc. you could select the range you want to apply to (say from E4:G8)
go to Home -> Conditional Formatting -> New Rule -> Use a formula to determine which cells to format -> Format values where this formula is true:

=COUNTIF($A$4:$C$6,"NRT")+COUNTIFS($A$4:$C$6,">=1",$A$4:$C$6,"<=3")

Edit:
if any of the cells contain 0,4-7 or N/O makes it white, then maybe:
=COUNTIF($A$4:$C$6,"N/O")+COUNTIF($A$4:$C$6,0)+COUNTIFS($A$4:$C$6,">=4",$A$4:$C$6,"<=7")=0