In order to determine which bag has the smallest unit price, we take the price and divide it by the ammount of ounces, that is:
[tex]\frac{2.50}{80}=0.03125[/tex][tex]\frac{2.25}{70}=0.03214285714[/tex][tex]\frac{2.40}{75}=0.032[/tex][tex]\frac{3.00}{100}=0.03[/tex]Comparing these prices per ounce, we will have thaat the store with the smallest unit price wil be the store in D, since it offers one ounce per $0.03.