A dealer bought an item for $ 7, sold it for $ 8, bought it back for $ 9, and sold it for $ 10. how much profi t did she make?

Well she starts with $7 and gets $1 the first time by selling it one dollar more than she bought it for. Then she loses nine dollars so that's $1-$9 which is - $8. Then she makes $10. So that would be - 8+10 which is 2. So she made $2 profit.