[求助]PREP中的一道数学题

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 of 100 units of cuntry R's currency and 1 percent of one's annual income.

which of the following represents the simplified the formula for computing the income tax, in country R's currency, for a person in that country whose annual income is I?

请问下这道题题干问的是什么啊？（第一段）。谢谢。

恶心的average。。。害我第一次也很晕。。。

说的是100货币单位和1%年收入的average，所以就应该是2%I+(100+1%I)/2

化简可得答案