[求助]prep一道数学题，后天就要考试了，好紧张啊~

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 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 i?

答案是50+i/40，可是这道题是怎么理解的呀，我连题目都没看懂，大家来帮帮忙吧~~~