Instructions
Take the chicken across the river. The fox won't eat the chicken feed and the chicken won't get eaten by the fox. Leave the chicken on that side of the river.
Go back across the water and grab the chicken feed. Go back across the river and leave the chicken feed.
Take the chicken back across the river to where the fox waits. The feed is safe from the chicken, and the chicken is safe while you're with it and the fox.
Leave the chicken and take the fox back across the river to the feed. Leave it with the feed. It won't eat the feed when you leave it alone.
Go back across the river and grab the chicken. Bring the chicken back across the river. You have successfully moved each object across the river without any of them being eaten.