You need to write a program in any language that will produce (source code for) a program in a different language. That program will produce a 3rd program in another language and so on.
You should aim to create many programs; you aren't limited to 3. You can re-use a language, but it won't be counted in the scoring.
Your entry is the source code of the first program, together with a list of the languages of subsequent programs produced in the order they are produced. For easy reading maybe include each program's output/source.
Scoring will be the length of the source code of the first program divided by the number of different languages used.
To prevent solutions such as
1 (that has been pointed out in the comments) I suggest the following extra rule:
The output of one program must not be valid code in the language of that program.