Please could you translate the following:

Sen cok guzelsın.sen muslumansın demı....

Tesekkurler

My try as learner.

The first sentence - "Sen çok güzelsin" - definitely means "you are very beautiful".

As for second, I suppose that "demı" means "değil mi", that is "isn´t it/aren´t you" here. With this assumption, the second sentence would mean: "You are Muslim, aren´t you?". But this is just my guess about "demı" - we need to wait for someone who knows better.

Yes, "demi" is değil mi.