A man needs to ferry a leopard, a goat, and some grass across a river.
His boat is small, so he can only carry one at a time.
If he leaves the leopard with the goat, the leopard will eat the goat.
If he leaves the goat with the grass, the goat will eat the grass.
How can he ferry all three across?
Take the goat across.
Return, take the leopard, and bring the goat back.
Leave the goat, take the grass, and leave the grass with the leopard.
Then he can go back and safely take the goat across.
[a Tigray story from northern Ethiopia]
Inspired by: "A Tale Resembling a Riddle" in Tales, Customs, Names, and Dirges of the Tigre Tribes by Enno Littmann, 1915.
Notes: You can read the original story online. There's even a Wikipedia article about this folktale type: Wolf, goat and cabbage problem, along with other River-crossing problems.