A farmer has a wolf, a chicken, and a bag of grain he needs to get across a river. He has one boat to take them all across. He can only take one at a time. He can’t leave the wolf alone with the chicken or the chicken alone with grain. How does he do it?

He takes chicken first. He takes the wolf over second and comes back with the chicken. He drops off the chicken and takes the grain to the other side with the wolf. Last he goes back to get the chicken and brings him across.