If 4 croissants costs $2.60. how much would 1 croissant cost?

That easy first u divide $2.60 by 4 for which will give you 0.65, so that means that 1 croissant cost $0.65 :)

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.