请教一题 pre中的题目 谢谢 /   应该是说 看不懂他在问什么

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 unites 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 ?

 Ans : (50+ I/40 )

(1%I+100)/2 =Average

So Average+2%I=I/40 +50