Alright, so, we know that the team started at about 9 1/2 yards right?
Well, since they lost 9 1/1 yards after, we would go negative on the number line meaning that we would move 9 1/2 spaces to the left of the number line.
Now, when we move 9 1/2 spaces to the left of the number line, we get the answer if 0.5 yards.
Glad I could help