I don’t think Amazing Alex The Backyard level 2-15, called “Fort Box”, is suitable for guarding invaluable amounts of American gold, but I suppose it does an alright job protecting one gold star. In any case, position the rope and pail to the left of the hook so it will swing toward the books. Place the elbow joint just left of the top star, angled slightly upward so the tennis ball — placed above the opening — will travel a slightly further distance. This should help match the timing to cut the rope, sending the pail into the boxes.
If you have a different strategy for completing this level feel free to leave a comment below.
