If a businessman wants to cross the river, he must first assume that A, B and C are accompanied by A, B and C respectively. First, businessman A needs to cross the river with his entourage A, then A stays on the other side, and then A draws the boat back.

The two followers of BC then rowed across the river and C rowed back. Five AB two businessmen rowed across the river, Bb's master and servant rowed back, and BC's two businessmen rowed across the river.

Other analysis of businessmen crossing the river.

It is a common problem for businessmen to cross the river. In fact, this kind of question can be answered by logical thinking. But through the establishment of mathematical model, a general solution can be obtained, and through computer calculation, the scale of the problem can be greatly expanded.

At every step, when a boat is rowed from one shore to the other or from the other shore to the other, it is necessary to make decisions on the people on board (there can be several businessmen and waiters on the boat crossing the river this time). On the premise of ensuring safety (there are no more waiters on both sides of the strait than businessmen), all people will go to the other shore in limited decisions.