She should divide the length of the wall by the number of strips.
Step-by-step explanation:
We want each of our 96 stripes to be just wide enough so that all 96 of them cover the 15 yards long mural with no spaces left. To find the necessary width of the stripes, we just need to divide the length of the wall by the number of stripes:
This gives a width of 0.15625 yards for each stripe.