Nancy is making cookies for a bake sale. she needs a total of 4 pounds of chocolate chips. she has a 28-ounce bag of chocolate chips, but the store now only has 10-ounce bags. how many bags of chocolate chips does nancy need to buy?

She needs 3 more bags of chocolate chips. there are 16 ounces in one pound, since she needs 4 pounds you multiply 16 times 4 which it equals 64. then you subtract 64 with the 28 ounces she already has. it will equal 36 ounces, the store has 10 ounce bags then you think about how many ounces would be in four pounds (64 ounces) and how much she needs, so the answer is 3 bags. To check you just add 30 plus 36, 66 ounces, Nancy will just have 2 extra ounces.