Math calculations with java script

[eeyore]

Ok let me give you a bit of back ground. A friend of mine from the net gave me a bit of javascript to use in a project I am working on for a game called Dungeons and Dragons. It is a monster stat block calculator/creater.

I have managed to get most of the fields I want in place but last night I ran into a snag. The page takes info that is put into the fields and adds them together using the formula given in the Monster Manual to come up with the BaB or Base Attack Bonus. Now for every attack after the first the BaB is at -5. Now the part that does the math I don't know much about and can't figure out how to make the second part show up as 5 less then the first one.

The line that prints the BaB looks like write(" ",formR.edtBAB.value,"<br>");

I'm including the file in txt format for anyone wishing to look at it.