Explanation:

                   English                         mathematics

 Passed        65%                             55%

Failed           35%                              45%

Passed in both = 22% of total students 

Percentage of students who are passe in any of the English or mathematics or both =(65+55) - 22 = 98%

So, the percentage of students who are failed in both = 2% 

Therefore the total filed ( in both the subject) students =16