



 
Hi Tonya, I imagine an image that is something like his. I am going to assume that the numbers 9 and 15 are the lengths of the sides of the respective octagons. A scale factor is between lengths so going from the smaller octagon to the larger the scale factor would be the number $k$ so that $9 \times k = 15.$ Hence \[k = \frac{15}{9} = \frac{5}{3}.\] Let me know if my assumption is incorrect. Penny  


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