Answer:
Elle should buy 1 gallon of milk for $3.
Explanation:
In one gallon of milk, there are four quarts. So we can multiply the number of gallons by four to convert it to quarts.
(1 gallon)x(4 quarts) = 4 quarts in one gallon
4 quarts is greater than 2 quarts so 1 gallon for $3 is a better deal than 2 quarts for $3.