[求助]CXD数学P214页NO.91

题目：On a certain road, 10% of the motorists exceed the speed limit and receive speeding tickets, but 20% of the motorists who exceed the posted speed litmit do not receive speeding tickets, What percent of the motorists on that road exceed the posted speed limit?

A) 10.5%

B) 12.5%

C)15%

D) 22%

E) 30%

求助啊，题目有些绕 所以看了解答也没有明白！答案是B

为什么不是E 直接就是10%+20%=30%？

10% of the motorists exceed the speed limit and receive speeding tickets, but 20% of the motorists who exceed the posted speed litmit do not receive speeding tickets

就是说 有10%的motorists超速被罚 被罚的占了超速的 80%啊

啊！明白了 谢谢