Anyone know how you can beat lvl 3 single player? I have tried to beat it at least 10 different times with 10 different strategies.

It will be a lot easier if you start in Africa. Take out bonus areas. Then take South-America and Antartics. Then you can attack full force to Asia and you will prevail. Try couple of times. :)

Africa is a pretty good place to start out since once you take it, you've got a decent income and only 4 territories to defend. It's not the only starting point that gives you a good shot at victory, but it works well for most. Take note of what colors are on what teams. Try to attack both teams roughly evenly and when one appears to have a clear upper hand, go after that team and lighten up on the weaker one. Don't try to expand everywhere at once since more often than not, you won't have enough armies to sustain expansion in all directions. You only need to hold one territory of a bonus to deny the bonus from your enemies, so make use of that if you don't plan on taking the bonus just yet.

Oh wait that's the crazy challenge. Sorry. Still, start in Africa and take all of it, then push into other areas. Don't go into everywhere at once since you probably won't have the armies for it. You can deny an opponent a territory bonus just by taking of of the territories in the bonus, so even if you don't have enough armies to take the whole bonus, you can just take and hold one of the territories until later.

Thanks for the advice. i have finally beat the single player lvl 3. Now I am trying to find out how to beat the Europe challenge.

I got europe the first time! Just send all your airlifts to russia, that'll release pressure of you.