Given:
WXYZ = 8m
W'X'Y'Z' = 6m
Pls. see attachment if it is similar to the figure that should have accompanied this problem. I simply edited the details to fit this problem.
WXYZ * scale factor = W'X'Y'Z'
scale factor = W'X'Y'Z' ÷ WXYZ
scale factor = 6m ÷ 8m
simplify: 6/8 → (6÷2) / (8÷2) = 3/4
The scale factor is 3/4
