Help require to insert countif function and shorten the formula

Hi daffodil11,
First of all I thank you for providing me tips to make my formula more easier to read and understand. I will definately follow your guidelines in future.

Thank you for shortening the formula. However you missed a main condition that the should be passed in minnimum 3 subjects to get grace marks for passing.

I want to use this formula for all subjects.
The total of grace marks is limited to 15 only.
The table of grace marks is as follows:
Average ... Grace
20: 15
21: 14
22: 13
23: 12
24: 11
25: 10
26: 9
27: 8
28: 7
29: 6
30: 5
31: 4
32: 3
33: 2
34: 1
35: 0

It's same for all subjects and the total of all should be 15 only.

I'm attaching my workbook here for your better understanding.

Thanking you in anticipation.