[求助]prep 13 题

prep里的数学题

Before being simplified, the instructions for computing income tax in Country R were add 2 percent of one's annual income to the average(arithmatic 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 the country whose annual income is?

A. 50+I/200

B. 50+3I/300

C. 50+I/40

D. 100+I/50

E. 100+3I/100

选c,怎么算？

最后问题应该漏了一个I吧～－－0

原题的意思是，计算收入税的公式为，该人收入的2％加上[100单位的现金和1％收入的平均数]。（add后面是一部分，to后面是另一部分，这2部分相加）

根据题意，就是2％I＋（100＋1％I）/2

就可以得到C的答案了，关键是看清楚and和of的位置。