CAMBRIDGE KE HISAB SE WO MARKSHEET GRADES KE HISAB SE DETE HAIN USKO PERCENTAGE MAIN KAISE KAREN KYA YEH AISE HOGA?

SUBJECT 1: A = 90%
SUBJECT 2: A = 90%
SUBJECT 3 : B = 80%
SUBJECT 4 : C=70%

90+90+80+70=330 DIVIDED BY 4=82.5%?

KINDLY HELP