The scale factor is 4.
First you need to find the length and height of the squares.
Bigger square:
Length = 20
Height = 16
Small square:
Length = 5
Height = 4
Then take the heights and lengths and divide the bigger numbers (lengths in this case) by the smaller numbers (heights in this case)
*This is using inverse operations. Diving to get what to multiply, since scale factor is multiplying.
bigger shape LENGTH divided by smaller shape LENGTH:
20 units / 5 units = 4
bigger shape HEIGHT divided by smaller shape HEIGHT:
16 units / 4 units = 4
There’s your answer!
Also you didn’t really have to do lengths AND heights, only one, because you already knew both shapes were similar.
if you didn’t know:
the “/ “ symbol means divide