What you need to do is divide 8 3/4 by 3 1/2 feet. In order to do that, you need to change them to improper fractions. (35/4 and 7/2) Now, you can divide. You need to use the rule KCF (keep, change, flip) So, you will keep the first fraction, change the division sign to a multiplication sign, and flip the last fraction. So, your new equation is 35/4*2/7. Doing this, you get 70/28. Then, you need to simplify this fraction. When you do that, you get 5/2. Change that to a mixed fraction to get 2 1/2. That is your width. I hope this helps! :)