Conditional formatting with a number of conditions

[Mamta123]

The below formula doesnot work

=if(Num(Avg(Age) >= 10, Green(),Red())

also I need to add And/Or statement to this :

if brand is 'A' or 'B' and Avg (age)>10 then green else blue

and if the brand is other than 'A' or 'B' and avg(age) > 80 , then green else blue

This is very complex. Can someone help me with conditional formatting