(TeX-add-style-hook "ex7"
 (lambda ()
    (TeX-add-symbols
     '("insum" 2)
     "Rd")
    (TeX-run-style-hooks
     "babel"
     "english"
     "latex2e"
     "scrreprt10"
     "scrreprt"
     "fleqn"
     "openright"
     "expkg"
     "diffun2")))