Calculating points and divisions of students scores in excel

Hi guys

I want to calculate the points and divisions of students score as shown below;
first you have to change the numbers into letters
A IS BETWEEN 81-100
B 61-80
C 41-60
D 21-40
F 0-20

also you have to select only seven subjects that a student has scored highest marks.
if a student has obtained F in Civics , Mathematics or both and have got division I or II, then he/she has to be pernalized to division III.
Points adn division are as follows
I is between 7-17
II is between 18-21
III is between 22-25
IV is between 26-32
zero is between 33-35

when counting A=1,B=2,C=3,D=4 and F=5
forexample
Anna CIVICS F, BASIC MATHS C, ENGLISH C,HISTORY B, GEOGRAPHY B, KISWAHILI C,BIOLOGY D, PHYSICS C, CHEMISTRY C. She has 19 points and division II but because she has scored F in civics then the points will be 19 and division III
example 2
Juma CIVICS F, BASIC MATHS D, ENGLISH D,HISTORY D, GEOGRAPHYD, KISWAHILI C,BIOLOGY D, PHYSICS D, CHEMISTRY C. he has 30 points and division IV
what will be the formula for solving this kind of excel problems?EDWARD.xlsx

Thanks
if you read carefully, i have written the points and everything is clear also look at the examples

Thanks
if you read carefully, i have written the points and everything is clear also look at the examples