No doubt this was a very primitive way of bartering animals, but it is an interesting little puzzle to discover just how many animals Jakes, Hodge, and Durrant must have taken to the cattle market.

• 这种非常原始的物物交易蕴含了一道数学趣题。你能很快说出杰克、霍奇和杜克三人各有多少头牲口吗？