Puzzle in Die Hard Movie! [Archive] - boards.ie: "The 3 gallon jug is the key.
Fill the 5 gallon jug.
Empty the 5 gallon jug into the 3 gallon jug, leaving 2 gallons.
Empty the 3 gallon jug.
Pour the 2 gallons from the 5 gallon jug into the 3 gallon jug.
Fill the 5 gallon jug and use it to fill the 3 gallon jug.
That leaves 4 gallons in the 5 gallon jug."
