I would say the last one (-8 + k, 8 + k)
It’s not (8k, -8k) cause that would be if we flipped it.
It’s not (-8k, 8k) because that’s what it is now
I don’t think it’s (-8 - k, 8 - k) cause that would be making it smaller
It’s (-8 + k, 8 + k) cause I think that would be dilating it
