[求助]一道PREP的数学题

cos

Before being simplified, the instructions for computing income tax in Country R were to add 2 percent of one's annual income to the average (arithmetic mean) of 100 units of Country R's currency and 1 percent of one's annual income. Which of the following represents the simplified formula for computing the income tax,in Country R's currency, for a person in that country whose annual income is I?

答案是50+I/40；自己推不出来，估计是没理解清楚题目，希望大家帮忙解下，顺便翻译下one's annual income to the average (arithmetic mean) of 100 units of Country R's currency 是什么意思，感激不尽！

iamliz

add （2 percent of one's annual income） to [the average of (100 units of Country R's currency） and (1 percent of one's annual income)]

(一个人年薪的2%) 加上 [(R国的100块钱)&(一个人年薪的1%)的平均数]

2%I + (100+1%I)/2

 = 2.5%I + 50 

cos

以下是引用iamliz在2008-11-2 21:33:00的发言：

add （2 percent of one's annual income） to [the average of (100 units of Country R's currency） and (1 percent of one's annual income)]

(一个人年薪的2%) 加上 [(R国的100块钱)&(一个人年薪的1%)的平均数]

2%I + (100+1%I)/2

 = 2.5%I + 50 

果然是我题目理解错误了，谢谢这位兄台解答~！

nitrogen

真是畜生一般的表达啊。。。 美国人真囧。。。