There are 20 maths problem in the test .for each right anwer ,you get 5 points .for no anwer ,you ge

题目

There are 20 maths problem in the test .for each right anwer ,you get 5 points .for no anwer ,you get 0 .for each wrong answer ,you lose 2 points instead of getting points .if Lucy gets a mark,which is prime number ,the largest number of maths problems she works out is ( )

答案

有20道数学题,答对加5分,答错扣2,不答得0,问如果Lucy的得分是一个质数,问你她答对的题目最多是多少?
满分是100,100以内的质数有2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,
最大的可能的分数应该是83,答对17题,错一题,2题未答.