If Formula

I am looking to write a formula in columns F-Q, that states If column d =12, then divided the sum of columns r and s across all 12 months or if column d =12 then divided the sum of columns r and s across April through October.

Thanks

Not sure what you are after, but I'll give it a shot:
Assuming you meant D=7 for second example, please try in F4 and drag across and down:

Formula:

=IF($D4=12,SUM($R4:$S4)/12,IF(AND(F$3>=12-$D4-1,SUMIF($E$3:E$3,">0",$E4:E4)<$R4),SUM($R4:$S4)/$D4,0))

Good luck!