formula for school marksheet

I prepared a school mark-sheet for teacher. But I facing a problem about following topic.
(1) If student get more than 33 % marks than one mark add each percent. But these marks limit is only 15.
(2) This grace marks will add in this subject which is less then 33.
(3) How to avoid #NA in cell when condition not apply.
Thanks

Mark sheet
SUBJECT NAME
No. NAME ENG MATHS SCIENCE TOTAL % RESULT RANK

2 ROBIN 60 35 29 124 41
3 CLERK 45 38 31 114 38
4 DHAONI 26 40 41 107 36
5 SACHIN 56 42 25 123 41
Hi, I send a sample for my problem, you can see for ROBIN 29 marks in science subject it is short than 35. So he is fail in exam but he gets gracing marks linked with % . If student has more than 35% marks, student get 1 mark more per percent. up to 15 marks for all subject which is short for passing.
FOR RANK I want that those student gets rank who is pass in all subject otherwise cell will left blank

Thanks, I will later try.