Answer: She need 18 inches of ribbon for her project.
Explanation:
Since we have given that
Length of ribbon = 60 inches
Part of ribbon cut off for an art project = 40%
So, Length of ribbon remains is given by

Now, Part of piece she only needs from cut off = 75%
so, Length of ribbon she need end up using in her project is given by

Hence, She need 18 inches of ribbon for her project.