Which is a better buy, a 24 ounce box of cereal for $3.69 or a 24 ounce jar of jelly that costs $2.29?

The jar of jelly is a better buy, because you pay 10 cents per ounce.

You need to find the unit price, you do so by dividing the price by the ounces.

3.69 : 24 = 0.15375 = 0.15 cents per ounce

2.29 : 24 = 0.09541666666 = 0.10 cents per ounce