prep上的一道题，求教！

lindadinger

stock    number of share
V               68
W              112
X                56
Y                94
Z                45

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 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?

我觉得是4，，，答案是15，不太明白为什么

chengshien

原来的range是112-45

新的range是118－36

AlphaBeta

偶不明白啊，能解释得清楚点吗

qiancheng

是什么意思啊？

cherry_xiong

(94+24-56+20)-(112-45)=15