I have table "studentmerit.dbf" having fields 1.Regno 2. appno 3.Name1 4.dob
5. matsec 6. physec 7. chesec 8. biosec 9. comsec 10. meritmarks.

I want to calculate meritmarks and put in the meritmarks field.

procedure for calculation: I have taken matsec and physec as compulsory subjects and third one is optional subjects i.e those whose student secured highest marks in chesec or biosec or comsec taken for calculation arrived at a base 200.

(Ex) (matsec+physec+optional subject)/3

janono appno name1 dob matsec physec chesec biosec comsec merimarks
30001 12001 sakthi 11/08/1995 185 190 185 178

30002 12002 kumar 25/08/1994 190 175 185 192

herewith i attached sample studentmerit.dbf as jpeg image

how to calculate merit?