Conditional formatting .............

Hello All !!!

Cells A1, A2 & A3 have variable values in them !

1. If all 3 cells have the same value what formula do I enter into conditional formatting to make the background appear GREEN?

2. If 1 of the cells has a different value to the other 2 what formula do I enter into conditional formatting (as a 2nd condition) to make the background appear RED?

3. Same again but this time if all 3 cells are different in value ?

Many Thanks

Carl, London