displaying results of calculations with php&mysql

Hello I am pretty new at this but trying to create a database that calculates student scores and displays them on a weekly basis. I have gotten to the point that I can display the static data in the database for the particular time period I want in the format I want . However, whenever I try to do any calculations and display them, it's a no-go. I need to calculate sums and percentages for each of the rows and columns in the table. I have not been able to find any examples that show how to do what I am trying to do. I wonder if anyone could take a look at the attached file and point me in the right direction. Thanks, Scott Wagner