求教PREP上的一道计算收入税的数学题

如题：

before being simplified, the instruction 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 X?
A, 50+X/200
B, 50+3X/200
C, 50+X/40
D,100+X/50
E, 100+3X/100

求教~并希望能解释一下“were to add 2 percent of one's annual income to the average（arithmetic mean）of 100 units of country R's currency "如何理解？

是选C吗？如果是的话： 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

A+B

这句话的意思就是，要计算所得税，就将年收入的2%*X+（100元+1%*X)/2.

100 units currency,是指100个其本国的货币单元，也就是100元。

所以你算下来，就应该选择C

是选C。

楼上的兄弟能再解释清楚一点么？如果可以的话，能否翻译一下引号里面那句话？