Kevin got $$80\textbackslash\%$$ of the problems correct on a $$25-$$problem test, $$ 90\textbackslash\%$$ on a $$40-$$problem test, and $$70\textbackslash\%$$ on a $$10-$$problem test. What percent of all the problems did Kevin answer correctly? (2010 AMC8 Problem, Question \#9) 
选项为:A:$$64$$  B:$$75$$  C:$$80$$  D:$$84$$  E:$$86$$  请回答其中一个选项.