hello

i have had alot of help on these forums already and i thank those that have helped me thus far.
but i am having some troubles doing a query.
i am trying to get a students grade.
but each assesment they do has a differant weighting.
for each assesment they are given a percent for it say 80% which may have a weighting of 30.
while another assesment they have they get 52% but it has a weighting of 60.
and if they missed an assesment it doesnt affect there grade.
so what i am asking how can i get there percentage at the end of all the assesment and then turn that into a grade like B+.

to better show you what i mean here is the end report i have to make which shows how subjects have weighting.
http://i18.photobucket.com/albums/b145/hi2chriz/1stPage.jpg
http://i18.photobucket.com/albums/b145/hi2chriz/2ndpage.jpg

hope i was clear

still having trouble, if anyone could help me would be much appreciated.