Answer:
20ft
Explanation:
You multiply the model length by the scale factor to find the actual length. If the scale factor is less than zero, then the actual size will be smaller than the model. Therefore, your answer would be 20ft.
Specifically, the scale factor is .8 if the actual size is 20ft, 1 if the actual size is 25ft, and 1.2 if the actual size is 30ft.
