To be able to answer this item, we are to convert the price units to a unit that has the same units of measure for the volume. For the purpose of unity, we use gallon as our basis.
For Gasoline:
Gasoline : $1.94 / gal
For Soda:
Use the conversion factor, 1 gallon = 3.79 L
Price = ($1.64 /L) x (3.79 L / gal) = $6.22/gal
For Milk:
Use the conversion factor, 1 gallon = 4 quarts
Price = ($0.89/qt)(4 qt / gallon) = $3.56/gallon
The least expensive of the items is the gasoline.
