A post about jugs.

Which is not about what you might think.

The bat cost a dollar five cents, which is all in pennies, kept in a jug.

There are two solutions.

Fill the five-gallon. Pour three gallons into the other jug, Empty the three-gallon, and pour the remaining two gallons into the three. Fill the five-gallon again. Fill the three-gallon jug from the five. There are four gallons remaining in the five.

Working the other direction, fill the three-gallon jug. Empty it into the five-gallon jug. Fill the three-gallon again. Fill the five-gallon from the three. Empty the five-gallon container. Pour the one gallon from the three-gallon container into the five. Fill the three-gallon container, and then empty it into the five, making four gallons.