Having some trouble on this y+w=x for y

You have to find out what y is + w to get x

You want to get Y by itself. Subtract the w and get y=-w+x.

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.