Phillip needs to take the rabbit across first, leave it on the other bank and then go back to the first bank of the river. Now, he can get either the fox or the lettuce it doesn’t really matter. When he gets to the bank with the rabbit on it, he can drop off what he brought and then (here’s the kicker) get the rabbit and take it back with him to the first bank. Now, he needs to leave the rabbit there and get whatever is left over (the lettuce or the fox) and bring it across the river. Now that the fox and the lettuce are safely on one side of the river, Phillip can make his last trip across, pick up the bunny, and bring him back across to join the party.