Analyze Student Attendance Data

I have a very large spreadsheet with over 15K rows.  The spreadsheet is an export from our student information system of student attendance data for the second reporting term (10/11/23 - 12/21/23).  In the spreadsheet, you'll find the attendance code for each day of the term for each student.  My objective is to calculate the attendance rate for each student and then calculate an attendance rate for each home room.  The math is simple, my problem is figuring out how to organize the data.  I need to count the total days the student was in attendance and divide by the total number of days enrolled.  Then I need to average that percentage for each home room.  Linked below is my spreadsheet.  https://1drv.ms/x/s!ArjwgnKYAFBslSAgYSEYlDEvicyT?e=MXnw8i

Any help would be appreciated.  Thank you.