production report update from packing report.

dear friends i want to update my first sheet from second sheet.second sheet our packing report & it's daily I'm getting from packing department.according to packing report i want to update production sheet.second sheet Column "F" first 6 characters i need to mach with first sheet column "K" first 6 characters.if it is match then first sheet column "J" values need to reduce form second sheet column "G".
ex- first sheet value = 60
packing report value = 50 then answer in first sheet column "J" =60-50 = 10
after updating first sheet column "J" any value coming mines then that row need to delete.
pls make macro for this.thanks..