What you have to do to get the answer is multiply 3 pieces times 3 1/2 yards each. Get that length, and call it A. Then, multiply 5 pieces times 2 1/4 yards each, and get that length. Call it B. Then your answer is 24 - A - B.
Whenever the word problem says, how much is left, it's a pretty good bet that you're going to subtract.
Where specifically are you having trouble? Do you know how to translate word problems into the arithmetic? Do you know how to multiply a whole number and a mixed number? Do you know how to subtract mixed numbers from whole numbers?
If you show us what work you have done so far, we can probably spot where you're having trouble much more quickly.
Please don't call tutors names here. Everyone is volunteering their time to help students with math problems, and Denis was just asking a question about where you're stuck. Please read the "Read Before Posting" comment, which is available in most of the forums (although for some reason it seems to be missing in this one). That will tell you that the best way to get help on a real help board like this is to show whatever work you have done, even if it's wrong.