Answer:
9.1
Explanation:
For scale factor you divide one of the shape dimensions by the other one.
like if you knew the width or something of both of them you divide that one by the other one. So I chose:
91 divided by 10 = 9.1
81.9 divided by 9 = 9.1
54.6 divided by 6 = 9.1
So the answer is 9.1 no matter what you choose for this problem.