Bob is quiet. Bob is red. Charlie is blue. Dave is red. Dave is round. Gary is rough. Gary is white. If Bob is rough then Bob is blue. Quiet people are green. If Bob is white then Bob is round. If someone is round and white then they are rough. Blue, red people are quiet. If Bob is green then Bob is white. If Gary is red and Gary is not green then Gary is blue. If someone is quiet and not blue then they are not rough.
Gary is not green.