I want to Grade students based on their scores in five subjects.

Student's Name Physics Chemistry Biology Algebra GeometryTotal RANK GRADE
John 10 10 10 10 10 50 1 A

I want to GRADE the students based on their scores in the five subjects…
The total is calculated in the column H
[ SUM(c2:g2) ].
The students are ranked based on their scores [ RANK(H2,$H$2:$H$21) ]..
Now for Grading the students,
I want to grade the students in this fashion..
The Ist 20% based on the rank - Grade A
The IInd 20% based on the rank - Grade B
The IIIrd 20% based on the rank - Grade C
The IVth 20% based on the rank - Grade D
The Vth 20% based on the rank - Grade E.

Please find the attachment below.