e.g. for 75% labs 25% exam
disable the irrelevant fields by forcing 0% remains the labs 12.5% each and the exam 25% define course grade with real value, number id CG and calculations e.g. for 75% labs 25% exam =[[lab1]]*1.25+[[lab2]]*1.25+[[lab3]]*1.25+[[lab4]]*1.25+[[lab5]]*1.25+[[lab6]]*1.25+[[exam]]*2.5 define define total with letters 80%=A 60%=B 40%=C =[[CG]]
this way, students can see both, total results /100 and their grade as a letter
you can change and fix the ID numbers for labs and course items in their respective settings page
look down for this sub-menu > common module settings