问答题 A farmer buys a horse for $ 60. He sells it to his neighbour for $ 70. Then he discovers he could have made a better deal. He borrows $ 10 from his wife, and buys the horse back for $ 80. He then sells it to another neighbour for $ 90. How much money did he make?

【正确答案】

【答案解析】$10 第一次买马花费$60，卖了$70，共盈利$10。第二次买马花费$80，卖了$90，再除去借妻子的$10，共盈利$0。所以，通过两次对马的买和卖，他共盈利$10。