What would the final cost be for a hat that originally costs $16 if you have a coupon for 13% off and you have
to pay tax of 8.5%.

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.