Answer:
16:9
Step-by-step explanation:
If a rectangle made with a 16:9 ratio is cut into another rectangle and a perfect square, the rectangle will also have a 16:9 ratio. This could be done forever, leading into a sequence of numbers that adds from its previous number. i.e. 1, 1, 2, 3, 5, 8, 13, 21, etc
