Hi, from our initial setup we know that Y is 4, t/w are 5 and 7, s is 6, and that the first and third positions must be red, and the second must be green. If we put X in third we know that the two remaining spots belong to Z and U, and since Z is before U, we know that U must be second, and thus green. We do not know about the colors of slots 567.
