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Mrs. Campbell is making holiday treats. She needs 5 cups of flour. She has 1 1/3 cups of flour. How much more flour does she need?
"How much more," indicates we are looking for a difference in what she needs and what she has. Subtract.
Answer: 3 2/3. If you got it wrong, check to see that you borrowed. When you only have a fraction on the bottom, you can't just drop it down or you've not subtracted it!