Q18: Last year the price per share of Stock X increased by k percent and the earnings per share of Stock X increased by m percent, where k is greater than m. By what percent did the ratio of price per share to earnings per share increase, in terms of k and m? A. k/m % B. (k-m) % C. [100(k-m)]/(100+k) % D. [100(k-m)]/(100+m) % E. [100(k-m)]/(100+k+m) %

我读不懂题：（，答案是D。请NN指教

去年股票X每股价格上涨了k%，每股收益上升了m，(m>k)

问：每股价格与每股收益的比例值上升了百分之多少？

用K和m表示

设去年的比例是x:y

今年的是(1+k/100)x1+m/100)y

化简为(100+k)x100+m)y

比去年增加了(100+k)x/(100+m)y-(x/y)

=(k-m)x/(100+m)y

比去年增加的百分比为：

今年的比例(k-m)x/(100+m)y除以去年的比例x/y再乘以100%

就是100(k-m)/(100+m)%

不知道能否说明白