The table shows the number of shares of each of the 5 stocks owned by Mr.Sami.If Mr.Sami was to sell 20 shares of the Stock X and buy 24 shares of Stock Y,what would be the increase in the range of the numbers of shares of the 5 stocks owned by Mr.Sami? 题目什么意思不是很懂,有谁能帮我解答下啊?。。。